I think it’s probably true that non-straight couples meet up online most of the time. But I also don’t think that that demographic would have much sway on the graph at all. Only 7.1% of adults in the U.S. identify as LGBT, despite the skewed demographics online.
Seems the main difference is the OP graph has straight couples meeting in a bar going up and the one you linked shows a fall for all couples.
I would conclude that more straights hooked up in a bar while the non-heteros used apps to make sure the person they were hitting on was like-minded.
I think it’s probably true that non-straight couples meet up online most of the time. But I also don’t think that that demographic would have much sway on the graph at all. Only 7.1% of adults in the U.S. identify as LGBT, despite the skewed demographics online.