Plant-based is another word for "not vegan enough", and when one suggests someone should use the word plant-based they're telling that person they're "too far from the ideal vegan definition to call themselves vegan". It is very defeatist approach, and IMO harmful.

We should embrace the fact that in our societies, perfect veganism is a very extreme idealistic endpoint. Its the travel towards it which is already good. Heck, everyone who's not even vegetarian but reducetarian is doing a lot of good for both our environment as well as animal welfare.