I think you're right about P4, but P3 (at least from the FeMC perspective) wasn't really like that. You had to progress though the relationship in a specific way to enter in a lovers route. I haven't really explored this in the male path, but the female lovers path for most of the characters had very much to do with hanging out intermixed with carefully timed flirtation (I remember in Akihiko's case, you need to flat out hit on him to activate a lovers flag) and understanding of their feelings. You could absolutely progress from beginning to of a social link to the end one as just "friends."
P3P was like that because they were able to take already established characters that people were familiar with and configure Social Links in that sense. Again, I was glad with how Junpei wasn't a romanceable option in the female side for P3P. When I talk about this, I'm mainly referring to the male side of P3 and P4 as a whole.