The Catch philosophy of not playing off your back, but if forced to either get up or go for a quick submission, is a really effective one for MMA. If you watch even the BJJ guys who have the most success off their backs, they basically either stand up right away or try for a quick sub and if they don't get it work to stand. The idea of slowly working for a sub just gets you beat up against good top players (which everyone in the UFC is, relatively speaking). I really think that unless your goal is gi BJJ competition, developing a very complex open guard is largely a waste of time (unless of course you just enjoy it). Most of the best bottom players in ADCC, MMA, and no-gi in general have very simple but aggressive guards reliant on just a few sweeps and subs, and the ones with good TDs or leg locks will often optimize their guards around either just standing back up or attacking the legs respectively. I think one reason you see Americans and other nationalities catching up faster in no-gi than gi has less to do with wrestling and more to do with the fact that while Brazilians who grew up in the gi often have ridiculous guards and guard passing, in no-gi those skills are less valuable and you can catch them by having a more aggressive TD, leg lock, and what I'll call funk submission game (lots of emphasis on things like the crucifix, front headlock, truck, etc. that are much less utilized in gi BJJ). It's effectively easier to catch up to the Brazilian champs in no-gi because they have less of an edge in technical proficiency, since a major area of their technical skill becomes drastically less useful with the pjs.