Yes. Initially, it was a relic from the typewriter days, and the tabbing and indentation was developed to allow each of the affiliated tradespeople involved in the project to do their jobs effectively. But now, it has its own reasons.

One page in a standard format screenplay translates into roughly one minute of screentime. There are exceptions to this rule, but the first thing someone in the business does when they get a new script is check the last page number.

Further, when a screenplay goes into production, the work for the day is organized into eighths of a page, which is used as a shorthand for how long each piece of work is going to take.

So while changing the tabulation and type spacing might make a screenplay more readable, it would make it much much less produceable. At the end of the day, a screenplay isn't meant to be read, and the formatting reflects that.