Land definitely needs to be taxed, but not without the zoning changes first to allow more to be built on less.
This inspires a lobbying and public outreach effort to try and convince people that relaxing zoning rules will fix everything.
As with many corporate lobbied for campaigns, it may be a good idea in general (e.g. net neutrality) or it may not be but it's definitely never the panacea it's sold as by the well funded PR campaign.
Look at Japan, look at any metropolitan U.S. city that has actually leaned into it. Europe has had mixed use zones for effectively centuries and is not the dystopia that NIMBYs proclaim will appear in the absence of zoning.
It is unpopular because we subsidize the lives and assets of people who “have things” through zoning policy that they make.
And while every single reasonable but outdated justification for zoning has slowly disappeared, zoning has been thoroughly co-opted by greedy sociopaths and meddlesome wannabe HOA presidents who want to control their neighbors and police aesthetics and keep out undesirables and inflate the value of their investments.
I don't care if it is a panacea or not...If you want to convince me that restrictive zoning is not the most significant cause of our housing affordability crisis, you'd have to find some better proof than "developers like upzoning and developers are bad people".
Source for Seattle? I know there was a state law a couple years ago allowing for more housing, but I haven't seen reports of its effects.
Adding a dwelling unit won't solve the problem for everyone - but it will solve the problem for someone!
(Now there's perhaps an offset argument - if you can afford to build or buy, should you build so as to increase the supply?)