Yes, because muscle mass has absolutely zero advantages for their career/hobby. You said it yourself; Bruce encompasses everything. Citing runners is just as erroneous as referencing pure bodybuilders. They're only focused on one aspect of physical conditioning.
It's not hard to see what someone like Batman would look in real life. I'm merely a casual MMA watcher, but I've seen dozens of fighters with impressive builds, with the speed and agility to match. To a normal person, they would be shocked at how swift these muscle men can be.
With that said, I do still favor the leaner look. On the condition he is very well defined. Incidentally a good starting off point would be the oft-mentioned Scott Adkins (who I was never supportive of in the role btw):
Great physique, and he's already proven through his career it's the body type which is conducive to fluid and powerful movements. I'd actually be in full support of him being the main stunt actor for Ben. He even has the advantage of resembling Affleck.