The prevailing theory is that Meta did a 49% deal so it didn't set off anti-trust alarm bells. In other words, the 49% doesn't give them ultimate power, but you can best believe when Meta tells them to jump, the board and the execs are going to ask "how high?".

Yes, but Meta would be able to kick the board and find another one more willing to accept their proposal as the best for shareholders.

Power struggles like this are weird to me. Is kicking the board likely to succeed at 49%? If so it feels like the control percentage isn't the primary factor in actual control.

At 49% I'm certain they would become the largest shareholder, by far. Then allying with another smaller shareholder to get majority - especially as you are Meta and can repay in various ways - is trivial. This is control, in all forms but name.

another shareholder, one of the largest, is the now-former-CEO who now works at Meta. They have full control.

You only need to convince 2% of the other stakeholders to get your way.

They don’t have voting power.

There's a lot of things shareholders can do to screw over other shareholders. Smaller shareholders are at least somewhat likely to follow along with the largest shareholder, just to avoid becoming their enemies and getting squeezed out.