Boston College and SorryExcuse were "Founding Members" of the Big East Basketball Conference when it was founded in 1979 - it was founded as a Basketball Conference not an "all-sports conference" which is what JVP was lobbying for concurrently with the conferences founding. In any event, $hitsburgh, eeerrrrr I mean sPittsburgh, was not invited to join until three years later in 1981 and began competing in 1982.
Moreover, prior to the founding of Big East BASKETBALL Conference in 1979, PSU, sPitt, Villanova, Rutgers, West Virginia, Duquesne, GWU and UMass were the FOUNDING MEMBERS of the Atlantic10 4 years earlier in 1976 which was also a "Basketball only Conference" formed by many of the "Tradional Eastern Independent Major-College Football Programs" (specifically, PSU, ASWP, Rutgers and West Virginia). The other "Eastern Independent Major-College Football Programs" - SorryExcuse, BC and Temple competed in the ECAC Division I Tournament from 1975 until the Big East Basketball Conference was formed in 1979.
I don't know that much about it, but the ECAC was not a true "Collegiate Sports Conference" - it was a "loose affiliation" of schools that sponsored a DI Basketball Tournament at the end of the season prior to NCAA Tournament (they also sponsored DII and DII Tournaments) for teams that were primarily Independent (e.g., not affiliated with "all-sport conferences") and located on the Eastern Seaboard....they had "Regions" for the playoffs which were effectively New England, New York Metro, Middle Atlantic and Deep South. They offered their first tournaments in 1975 and I believe PSU was an eligible affiliate, but did not qualify. PSU then formed the Atlantic10 Basketball Conference in 1976 along with the other schools already mentioned. Syracuse, BC and Temple continued to compete in the ECAC post-season Tournaments until 1979 when the Big East Basketball Conference was formed by BC, SorryExcuse, UConn, G-Town, Providence, St. John's and Seton Hall. The Big East Basketball-only Conference then caused the collapse and reconstitution of the Atlantic10 Basketball-only Conference when it poached A10 Founding Member Villanova in 1980 and then poached the A10 again in 1982 in taking ASWP.
During the latter portion of the span discussed above - the Late-1970s and Early-1980s - JVP and PSU were lobbying the other "Traditional Eastern Independent Major-College Football Programs" - ASWP, SorryExcuse, BC, West Virginia, Temple and Rutgers to form a "Major College All-Sports Conference" similar to the ACC, SEC, B8, SWC, B2L8 and Pac10 which were in existence at the time. Several of the teams were in favor including WVU, ASWP, Temple and Rutgers.....the plan was to also ask Maryland to leave the ACC (UMd was a Founding Member of ACC in 1953) and join as a Founding Member as well as possibly the two major military institutions, Army in Westpoint, NY and Navy in Annapolis, MD. JVP was the primary, and most highly visible, advocate for the "Major College All-Sports Conference" for the "Traditional Eastern Independent Major-College Football Programs"; however, the Big East Basketball-Only Conference was against it from the start because only two of the Founding Big East Members played "Major College Football" (e.g., what would come to be NCAA Division I-A in the late 1970s) - BC and SorryExcuse. Well, BC and SorryExcuse decided to side with their small, primarily private-school friends in the Big East and actively opposed JVP's proposals for an "Eastern Major-College All-Sports Conference" and administered the "coup de grasse" by actively working on behalf of the Big East Basketball-Only Conference and secretly arranged for Pitt to be invited into the Big East in 1982 which not only completely divided the "Traditional Eastern Independent Major-College Football Programs" against one another on the issue, but also sent the Atlantic10 Basketball-Only Conference into a major tailspin as well given that the Big East had now poached the two strongest basketball programs from that Conference's Founding Members in 1980 and now 1982 (Nova and then Pitt respectively).
So you're only half-right in your assertions - the Big East was not an "all-sports conference" at the time, it was a Basketball-Only Conference in regards to revenue sports as was the A10.....the Big East did not even contemplate adding Football until PSU went to the B1G causing a major league problem for the revenues of their "Traditional Eastern Independent Major-College Football Programs" members. The Big East Basketball Conference - all of the Founding Members which included BC and SorryExcuse - invited ASWP in 1982 specifically to thwart and dynamite JVP's proposal for an "Eastern All-Sports Major-College Conference" and fatally divide the "Traditional Eastern-Independent Major-College Football Programs" one against the other (e.g., "divide and conquer") -- the Big East Basketball-Only Conference of the late 1970s NEVER had any intention of inviting PSU into the conference and converting it to an "All-Sport Major-College Conference" as this would have decimated three-quarters of its Founding Membership! JVP and PSU were the ENEMY to the Founders of the Big East Conference which was founded exclusively with Men's NCAA Major-College Basketball, and only Major-College Basketball, in mind -- they were never going to invite PSU nor had any intention of converting to an "All-Sport Major-College Eastern Conference" as JVP envisaged.
BC, SorryExcuse and, to a lesser extent, ASWP "made their bed" with their short-sighted, non-visionary, non-strategic thinking and as the saying goes, now they must sleep in it (the crappy overall revenues of the ACC relative to PSU's B1G Annual Revenues). F 'em.