Exactly. So the way the BECMI player handles a skill check is that he doesn't. The game that player is playing probably doesn't have Skills in it. Instead the DM would just have him make ability score checks, or just say via fiat whether or not the player can do such-and-such.
You then add on the Skill system to the base game, and now the 3 & 4E players have a system they are familiar with for their game that is a bit more complex than the BECMI player.
Skills were introduced later on in BECMI, and they were a part of the Cyclopedia. They called them "non-weapon proficiencies" but they were skills. You are correct that they were based on attribute rolls, however.
But I don't see this working. There is a chasm the players have to jump across. The GM says to BECMI player "Okay roll 1d20 under your Str". Player "Okay, my Str is 17, so here goes my 85% chance of success".
Then he says to player 2, Ms. D&D 3.5 "Okay make a Jump Check, DC 20". Player 2 says "Okay, I have +8 to jump, including my 17 Str, so here goes my 45% chance of success."
Then he says to player 3, D&D 4e Guy "Okay make an Athletics check to make this jump, DC 20". 4e Guy says "No problem, since I'm trained in Athletics, with 17 Str, I have +12 to this check, so that's a 65% chance".
So that's why I'm skeptical of the idea of 3 different styles of play being able to co-exist at the same table. This
is what they were saying might be possible; and I'm not saying it isn't. I'm just curious as to how they will do it.
One of the big challenges in a superheroes RPG is how do you balance a Captain America type and a Thor type on the same team? For years, most games answer to this question was "don't" or "make them both the same level". But there was another way to do it; nobody had thought of it yet; but it was possible. Giving the captain more Hero Points and letting him do cool stuff with those points was a solution I came up with and it worked.
That's what I'm thinking they've figured out here. A third way that nobody saw before to balance things. I'm interested in speculating on what that might be...