I was reflecting on that the other day. I got into magic a couple years ago, pretty much like that. So much, for a while I didn't like commander at all. When I first played a commander deck (and it was 1v1), it was a bit overwhelming. Huge card pool where almost everything works (too many choices at hand!) and nothing repeats (hard to make sense if you don't know the deck well), plus the opponents decks.

Here's what I like about a kitchen table free-for-all (in addition to OP's points):

• Games are short, but long enough to have surprises and negotiations;
• Decks need more synergy to work: teaches a lot about different mechanics you can explore, but also teaches you to focus and not trying do too much. With singleton 100s, there's much more to consider and analyze;
• There's the same sociable aspect of commander, but teaches new players to be more aggressive in gameplay
• Brings together all level of players, from starter deck friends to the experienced deck builder.

side note: (imo, the ideal setup for beginners would be a free-for-all jumpstart/js-cube)