I mean sure there is "some" truth to it. But more likely than not the acquiring company has two conflicting priorities:

1. acquire startups/talent to improve certain things that the company is incompetent at

2. actively block efforts from the startup because a certain part of the company actually believes that they are doing things better themselves, i.e. ego

I advised a big US car maker on their autonomy and one part of the company actually took 8 months to acquire PC's to do machine learning with(which then ran into a supply shortage further delaying it) and 5 months to upload test data to s3. It's not that they weren't working on it. They had meetings every week.

You give them too much credit. Of course there is probably also that one guy actually implementing in the middle of the 20 people that just talk who's plate is completely full. But that doesn't stop those companies from hiring 20 PMs with their own agendas to manage that one guy.

If you really need the money keep working there. If not either force change it and get fired or run away.

Someone in Germany called it the 3 A's.

A - Akzeptieren -> accept

A - Aendern -> change

A - Abhauen -> flee

EDIT: in the time I was there half of the team of the acquihire they made quit and moved on to better opportunities, because the org itself took almost a year just figuring out how to get these people to migrate their docs from google docs to office 365