It is, it makes the thread longer without adding anything new. A like button is much better for that kind of feedback.
Sigh
A like fundamentally, inherently, adds nothing new.
All it does is increase the polarisation of the debate. From my experience on other social media - and indeed the media in general - the most attractive contributions are those that are designed to inspire high emotions. Comments which employ hyperbole, emotional appeal or humour at the expense of facts are fare more likely to be 'liked' than ones which are actually the highest in quality. Likes encourage contributions which express very strong opinions, and there is inevitably a greater emphasis on those when people start competing for likes.
There is no need for any more tribalism on these boards than there already is. Liking will not encourage people to do more research, tolerate each other more or keep in mind mutual respect at all times. Competing for likes is counter-productive to these aims. And all to what benefit? Why, exactly, do you want to like a post? If you think it's great then tell the person who posted it so, and why, in just a few words. That will actually encourage more positive contribution. If all you do is agree with it, that isn't quite the same as liking something anyway. You can still express that with a very short post in the way I have done, or by using the words "I agree".