Yeah, but sometimes certain features can only be added when the company has a lot of money to back them.
Stuff like extremely fast buffering speeds due to good internet infrastructure to datacenters or elaborate DDoS protection for building entire clusters to cushion against huge data flows.
Or, if those are too technical, just think of the content creators on YouTube, who don't want to upload their videos to other platforms because YouTube is effectively a monopoly now, and so it would be pointless to give other platforms the time of day.
If not enough content creators give competitors the chance, then how can they be expected to grow enough to stand a chance, in the first place?