Fair point, but 6 years and 3 (?) CEOs is an eternity in startup years. It's effectively a different company with the same name now.
When Tencent, Sequoia and Andreesen Horowitz are in the same room, its a startup, specifically a tech startup.
They could be selling hairgel with only a landing page for you to put your email address and it would be a tech startup. They'll make sure it is considered as much.
Having said that, both Google and Amazon has excellent PMs and there are teams that require PMs to be in the loop for a feature launch but it is not universal.
Knowing what’s valuable and what’s not is a function of being an employee. Designers and engineers should know where value exists.
If they need a PM to shift them away from valueless work, then I highly question their efficacy as an engineer. I also highly question that organization’s management structure and communication.