Among other reasons, a lot of it is simply because everyone wants raw battery range and PHEVs are a huge compromise on battery range. Internal combustion engine

Among other reasons, a lot of it is simply because everyone wants raw battery range and PHEVs are a huge compromise on battery range. Internal combustion engines and gas tanks eat a lot into the weight and volume budgets of a car. You can fit a lot of battery in that weight and volume. We've got to the point where battery density is getting strong enough that a hybrid can't make a combined range as good as a pure EV either in the same weight class. Another reason is that if you design for the strengths of pure EVs, you can shift all of that weight lower and out of cabin and storage space, including offering new perks such as "frunks" ("front trunks"). A hybrid can't compete on cabin/storage space with a pure EV designed to be a pure EV, and can't quite compete on battery range.