That's a bit rude, isn't it? We follow your argument, we just don't agree with it because we think the reality is more nuanced than
You'd be right, except that we don't believe the implied premise is true, and the conclusion doesn't necessarily follow from the first two premises.
The reason why Riposte is so great for Battle Masters is because they have multiple superiority dice, their dice are larger, and they will typically do more damage per hit (whether because they're using a two-handed weapon or because they're using the Dueling fighting style). The risk of using Riposte is reduced (It's a risk because Riposte can miss) is lessened by having more resources and increasing the benefits (more SD damage and more weapon damage on a hit).
Meanwhile, characters with the Martial Adept feat only have one Superiority die, and it's only a d6. Riposte is not a safe risk to them because of very limited resources and smaller returns. It is better for them to use their single resource on a more reliable maneuver which can, at the very least, give them a guaranteed 1d6 extra damage, and at the most, can deliver an effect that benefits your entire party rather than just yourself.
And that does nothing to mention that the point of being a grappler isn't to do damage, it's to control your enemies. Riposte doesn't help with that at all, but many of the other maneuvers would.
And if you want to get into appeals to authority, the guru of grappling, ktkenshinx, rated Riposte purple in his grappling guide, and both his guide and the Art of War rated Disarming Strike, Menacing Attack, Pushing Attack, and Trip Attack as blue or better.
Riposte is a good maneuver, just not for this kind of character.
All of this! Disarming and Menacing are probably the two I'd take first. And I expect I'd also take Pushing or Trip well before considering Riposte.