Not sure where you got the idea that reading but not clapping on Medium gained anything, and I see that some folks just clapped, perhaps without reading at all. That in itself is an interesting social experiment.

Medium’s algorithm, when I first joined, took into account claps, reading time (how long a reader spent on the page — and that’s one reason why the stories are measured in time rather than number of words) and how much the reader supported each writer to determine “reader engagement”. Presumably, someone who liked your writing, read each piece, clapped and spent the appropriate length of time on the page was counted as a fully engaged reader and the writer was compensated with a percentage of that reader’s membership money.

As the site has grown, however, each story has received less and less money from the readers, even though they might be still receiving the same levels of attention. So something (or many things) have been changed (or broken) in the algorithms (or company policies).