100% yes. The actual format of the binary that the device interprets is treated as a trade secret, and the vendor tooling is the only documented way to target code at those parts.

This has various implications, such as smaller FPGAs being literally tooling-locked versions of larger ones, important features like partial reconfiguration being supported by the hardware but a huge pain to use from the logic, or vendor tools not supporting some language construct and you're stuck with that tool. (Admittedly they are far and away better than FOSS tooling for language support.)

They certainly do withhold information. See my other comment for my speculation as to why.

I suspect it has nothing to do with the OSSW community; they give their software tools away.