Well, yeah. If you simplify plots to the point of absurdity, there are probably only six. Here, I’ll simplify it to one: story starts, ends.

I do think, the analysis is interesting beyond the singular conclusion being highlighted in the headline, but yeah, to make it even more obvious how uninteresting that particular conclusion is, a little visualization:

Basically, that conclusion can be reduced to say that humans don’t like stories with 4 or more rises/falls, because all possible combinations for less than 4 are covered.

Oh geeze, no. This is reductive to the point of not being useful. The “plots” are just how much positive and negative things are happening in the story at certain times. This doesn’t cover anything that we’d be ambivalent about or anything more subtle than a good/bad dichotomy.