I watched that 2nd half, and I don’t even know if you could call it “great offense.” The Clippers went nuts % wise shooting pretty open 3s. It was great strategy. It certainly wasn’t GREAT OFFENSE v. GREAT DEFENSE. Sure, it’s an offensive league but Jazz perimeter defenders — including great offense Mitchell (which defeats your point to some degree) — were getting turnstiled, and much like hockey defenders nearest the goal look the worst, Gobert probably gets an unfair portion of the blame on that end. It’s a rock and a hard place for him if the first level defense in a 5 out is getting abused.
Not being able to contribute offensively to mitigate small ball is more on Gobert. But if Utah actually had a smidgen of perimeter defense, it might’ve been a different result.
Analytics say if you're within 4 feet of a 3 point shot, % complete declines from 40 to 30%, only a few 3 point shooters can make their own shot, most depend on getting a pass when open for a clean shot.
So yeah, perimeter defense matters, both a matter of IQ (knowing when to double and rotate) and speed/hustle, getting to the shooter without fouling him.
I'd fine my players $1K for every time they bite on a pump fake and foul a 3 point shooter. The point isn't to try to block the shot, but distract the shooter, all you need to do is get your hands up vertically and jump straight up, not at the ball trying to block it.