Because for many common usage patterns, plug-in hybrids get nearly all the emissions benefits of full-electric vehicles, but a practical for people to use who have a small fraction of use where a full EV would not currently be suitable for reasons of range and state of fast-charging infrastructure.

> isn't their goal to be all electric by 2050 something?

The real goal is reducing greenhouse gas emissions. But, a subgoal of that cited by the governor's executive order that this bill cites is a target to have “virtually all” personal vehicle transportation be zero-emission by 2050. Some (possibly even significant) share of personal transport being by PHV that are used mostly within their all-electric range would not be incompatible with that.

And, in any case, the PHV subsidy in the bill phases out more than 25 years before 2050, because PHVs are seen mostly as a bridge, not a end-goal solution.