There are way more renters than owners. Prices have been going up more than 5%. Owners are most definitely not the "less-powerful" here.
So in reality the gov't might be artificially surpressing supply (though it's mostly due to owner pushback), but the "manipulating prices" (trying to keep rent growth from getting out of control) is helping less-powerful.
I get the point about how this can default owners to just increase prices. Well they were going to be doing that anyways! Especially with surpressed supply!
Arguing that "overall price increases with this law" > "overall prices increase without this law" is non-intuitive and probably just not true.
(thought experiment: if raising 5% every year with the law made sense, why would it not make sense to raise it 5% every year without the law? This law doesn't prevent other owners from offering _lower_ rents, if the market calls for it)