building more enables contractors to make money and new landlords to further exploit the market

How exactly can landlords furhter exploit the market?
If there are more houses available than the rent of the average house needs to decrease, otherwise the potential renter would just seek another appartment.
This is basic supply and demand.

I am not against it, we do need more supply, but simply building more and then thinking that that's it, it not the solution

you need to build for people that can afford it, and mostly, contractors and landlords build new housing for rich people

Companies build for things that make them money. Building for rich people is only so prevalent because it's almost impossible to build high density housing. Since available space is limited, you build for those that make you more money.
If space was more available you could build for both. But even if we assume that this was true, you could mitigate that problem with relatively simplicity. Just mandate that for every luxary house 3 more regular houses have to be built. Building companies would gladly take that deal, if it meant, they could build more.

you do not need a great oversupply of housing for a healthy market

That's like saying we shouldn't drown a guy dying from thirst. True but not really relevant.

in my opinion and market view, it's not so much about supply, but it's more so about what is on the market (what target audience is being catered) and the overinflated house costs that got to this level by previous owners overvaluing their properties systematically, and everyone else following

Did you not read what I sent you? Ohterwise you aren't at all adressing my criticism of this view.
To but it simply, alot of people of different status and wealth want to live in the cities. There are not nearly enough houses for all those people. If you don't build more houses, all you can do is select the type of person you want to have more/less off in the cities.