so service is a weird thing: It's very easy to train but hard to train against, so your serve will quickly become a better shot than the average of the room, if that makes sense.
So you have that level where people will be able to do good serves but not return them, leading to a lot of frustration and points won on the serve. But then, at the next level, people will have learned to return the serves correctly and now the serve, however good it is, will rarely score a point. so it becomes "the service is just to start the game"
However, if you're playing against someone who can't receive (and you're playing to win), it's perfectly acceptable to do your best serve and get points from that. What you should be careful is to not rely entirely on that (which can be easy when your serve wins most points) or you'll basically win or lose on the serve, and to sometime not push your serve too much to let the play happen and practice other things (for myself, I like to serve strong on the best opponent and light on the weakest, to mix serve and point training)
But at the end of the day, if you respect the rules and are not otherwise a dick, that dude can fuck off