The problem is you (and many others, not singling you out here) believed you had rights on a privately controled web platform.
This has never been the case.
In the past reddit said and had "terms of service" that suited their business goals at the time. In the past, those goals were: Use VC money to grow the platform as large as possible as fast as possible.
Now that Reddit is looking to go public with an IPO, those goals have changed.
The goal is now. Generate as much revenue as possible from the user-base created with the VC money.