Sure, if you're a small builder you want to build ASAP for cash flow reasons. However over the past decade both the UK and Irish building markets have become dominated by REITs who do in fact benefit from increased land prices in the absence of building.
I mean, sortof. I get where you're coming from, but if a development has planning permission (i.e. it's allowed to be built) then it should be massively penalised if development doesn't begin pretty soon after this. As a society, it's problematic for a whole bunch of reasons to have companies sit on land that could provide housing when there's a shortage.
It's just more time and money wasted on people to inspect and enforce and run appeals systems (what if they had a good reason for not starting?) and write and update rules (what do we count as a good reason?). All of this costs endless tax money that could've been spent on building or buying houses. Or, in 2023, just buying enough food.
Fix the underlying issues, and people will build.
It might be worth considering how, if that were true, anything that has a capital investment required of it ever gets done. Building is not an expense to a building company. What do you think the company does to generate revenue, if it's not building?