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.