So, there is one notable way in which splits can have a practical impact on trading: options (and credit to Matt Levine for mentioning this recently). Options trading is still limited to blocks of 100. A split reduces the cost of those contracts.

I do wonder, with the relatively recent availability of fractional share ownership, if the effect of splits will be more muted in the future as retail is no longer limited to whole share purchases. But who knows, there's also a psychological aspect to this that's hard to account for.

My finance classes are at least partly a few decades out of date :-)

Another reason that I recall is that (presumably) if a company does a split, it indicates that management is confident in the future--and a reverse split presumably indicates the opposite.

>I do wonder, with the relatively recent availability of fractional share ownership, if the effect of splits will be more muted in the future

Certainly, we've seen share prices of a fair number of companies recently that would have been considered well out of "normal" ranges historically.

Another: brings in more retail traders who base their decisions on the price of the stock