I agree mostly but take issue with "not needing managers". As someone who went from split shows to big venues to touring, managers (good ones) are a godsend.

Will there be convenient parking?

Do they have adequate power?

Is the stage big enough?

Do we need to book sound?

Is there a weather contingency?

Where can we sleep?

What time is load in?

What time is sound check?

What form of payment?

How will they be advertising?

Who do we give promotional materials to?

Etc etc. Having someone take care of all this stuff allows us to focus on practicing and recording (which has another long list of questions that need to be addressed).

Not to mention networking and venue access. Put all that stuff together and it's a full time job that artists are poorly equipped to handle.