Unironically it’s the solution. The problem is that no one can make the investment.

If housing wasn’t an investment that would imply no returns, and thus no incentive to build and thus far less housing.

Housing would still be built, but not as an asset for which appreciation would be expected. Your argument is like saying that unless cars appreciate in value, no cars would be built.

Cars do not have land which is inherently scarce. A better comparison is an RV, which is indeed rare.

Also, I did not say houses wouldn’t be built - I said there would be fewer which is just the truth.

All else being equal, lower return on houses would result in fewer being built.

But all else wouldn't be equal, since regulatory barriers would be removed.

Indeed, your notion that houses would be spoiled as an investment, and fewer would be built, are contradictory. The former requires so many are built the market would be saturated, preventing appreciation.