So far, there are only theories about what is the purpose of changing the toe angle of the wheels, but the benefit is not established. Whether it is helping in ride height OR in some form of drag reduction OR helping tyre life. Once that is clear, only then the actual performance gain can be hypothesized. Because it is Mercedes, the hype/controversy is much bigger. I don't if this is something that Renault or some mid-field team would have done, anyone would have bothered.
Mercedes are a team with deep pockets who would be happy to invest into anything that can give them gains, no matter how small the gains are. There was question mark and controversy when the new wheel rims were introduced in 2018. Now there are a few teams who are using similar design, but that seemingly hasn't really yield any great benefit.
A new one, as long as its last. 
