Ultimately it’s a bit too much effort to decide “oh gee exactly how do I feel about this post, let me think for a bit”, so as a general purpose one-size-fits-all thing, I believe reactions is a poor fit – it’s more of a specialized tool for some communities and perhaps smaller communities. I could certainly see it getting use in communities where they want upvote (thumbs up) 
and downvote (thumbs down) 
. Now they can! Install reactions, and make those the only two available options on each post.
In contrast, “my heart goes out to you” is a fantastic general purpose solution. Love is indeed, as they say, universal. And you can always remap the heart to some other icon, if you prefer. Here’s a great example I just saw! I’ve met Tim (once), and I pressed 
on this post. Now, does any rational human being looking at that reaction count actually think that all those people meant “yes, I like that you got hurt, Tim!” 
Obviously, no. It means “my heart goes out to you”. This is not a difficult thing to understand, not even a little, and anyone who tells you it is… is trying to sell you something 