Apparently you're right that MV3 only restricts extensions, not native blockers. I stand corrected on that part.

However, uBO on MV2 still has features that no known native ad blocker on a Chromium-based browser offers.

The closest match I could find is Brave Shields, but it still lags behind on per-site control, mainly because it has no dynamic filtering matrix, and it has no logger comparable to uBO's. That most of the list i already mentioned multiple times.

To date, nothing matches or beats Firefox + uBO, so the original point still stands. The burden of proof that shows the contrary is on you for that.