Equalizer size physics

I know questions about the equalizer size have been asked ad nauseam, but my question is about the physics.

What prompted this was a coworker posting photos of a recent install on reddit which yielded the comment "your equalizer is too big" referring to the pipe size.

Because the pressure once equalized will yield no flow, and we're only talking about a few PSI there's not much to equalize so for pressure equalization a very small pipe would suffice.

As far as water traveling through the equalizer, that would be water carried by the steam which left the boiler's supply or condensate that might return via the main. A too small equalizer which restricts water return could be a problem, but how could too large of an equalizer be a problem?