You can't "affordable housing" your way to cheaper housing or rent. It can help with reducing displacement, but it increases the cost of the market rate units. The overall problem is a lack of supply. Portland recently passed an IZ ordinance and it had devastating effects on new housing construction.

The municipality that I'm in lets developers ignore the state-wide law that mandates certain amounts of affordable housing to be built in new developments. The developers and real estate investors that are government officials also don't like to recuse themselves from such matters, either.

nobody even sued them or the city for damages?

Who would do the suing? The people that can barely afford the housing? Surely it's not going to be the city, as the developer is more than likely in cahoots with the people that would be doing the investigating. Maybe I'm too cynical, but I've been in/around this world too long to see it as anything but cynical.

It seems like either a typical class action suit. The city's negligence/unenforcement led to higher rents in that neighborhood.

Or could be even easier to show that the lack of said units led to displacement for actual families.

I'm not saying it's easy peasy but if affordable unit advocates believe they are important then logically enforcing the regulations they fought for shouldn't be just shrugged off, at least as a signal to cities and developers.