After: FB now owns the market; how did we let them become a monopoly!?
Before: FB doesn't own the market.
During review: FB would (/not) own the market with this acquisition. So we should deny (/approve) the acquisition.
After: Look the outcome we expected!
Much later: wow things change over time!
The original comment said monopoly, not anti competitive behavior. They are different, you're right.
> They don't need a de facto monopoly to have an adverse effect on competition or their consumers/users.
True. That said, i'd argue facebook actually has a positive affect on competition in their space. They're regularly rolling out new features and making changes due to competitive forces, meaning others compete on better experience rather than just different.
Eg. FB copied snapchat stories... and snapchat had nothing to stay relevent. FB copied tiktok format and TT is stronger than ever, since TT's advantage wasn't the format but the algorithm.