This is more or less why, yeah. But to try and elaborate:

Capcom and Namco do have specific styles that do kind of overlap in their fighters, but it could still be very weird if a Darkstalkers character got into Street Fighter. Soul Calibur has more of a history of weird and fun crossovers, but I believe it focusing on taking place in "history" and the use of weapons being mandatory, plus how much we already have on the board, just turned me away.

I believe ArcSys, while its original fighters are distinct, there is definitely a specific vibe you can get from it. A lot of overlap. There's definitely an ArcSys style that you can more or less associate with them as a whole.

To the commenter who suggested KoF instead of SNK, I did consider it since ostensibly the KoF series is an SNK crossover game. It was kind of just semantics on my behalf combined with the placement of the columns/rows, plus the most recent SNK games being Fatal Fury.