Do the workers at a startup own shares? That means the workers own part of the company. If they chose to raise more capital, that's their decision. Even the most socialist leaning coffee shop will raise capital to pay for capital improvements.
But the reality is that startups workers usually have shares and the shares make them owners. Whether they benefit or not from the ownership isn't the question here.
All you need to do is look at some union-run cooperatives that fail to understand that "worker owned" is not magic.
Do you think that some magical worker-owned cooperative would let people sell? No way. I know folks that worked at a vegan restaurant cooperative. They wanted to get another job-- but the cooperative wouldn't give them anything. Why? If they weren't working each night, they weren't going to get a percentage of the business they built.
There are good reasons for lockups and, of course, you don't need to take the job.