Can someone explain to me why this is a "good" thing?

If solar is too cheap, it won't be overbuilt... or people will lose their return on investment => less solar.

Unless I am missing something major, another way to say this is "solar power during peak solar flux will become so valueless that people will stop building solar".

To the downvoters: Off-grid solar will be unlikely to be dominant energy consumption, and there are other options to build cheap, efficient and clean energy. Solar is an option and I don't "hate" solar.

This is a simple argument of negative prices or low-cheap prices will correct themselves on the market without external forces like subsidies from tax payers... which means it isn't nearly as cheap as everyone is saying.