System Matters Only As Much As Your Table Needs It To.
The main issue with the interminable ‘system matters’ debate in tabletop role-playing games is that it’s perpetuated by shitheads looking to game the online attention economy for crumbs. Anybody claiming that they know better than you and your friends at the table how you should play your games almost invariably does not do so with your best interests in mind.
That is not to say that ‘system does not matter’, but that any system you elect to use should always serve the needs, wants and enjoyment of you and your friends at the table, and never the other way around. If a mechanic in a game is causing frustration or discomfort at your table, rip it the fuck out. Discard it. Designer intent be damned. Likewise, if you or your table need structure or precision where none exists in your rulebook of choice, pilfer it from another text, or even better, make something up.
Role-playing games are, at their core, games of make-believe. Systems as usually described inherently cannot be imposed on players because they are simply ideas, communicated in writing. The rules, procedures and shared imaginative spaces of role-play rely entirely on the mutual consent of their players, and anybody seeking to impose constraints on that externally, either by claiming that a game designer knows better, or that their advice will make you a better referee or player, is a fucking dweeb unworthy of your attention.