AirBnB actually solves a lot of this problem, though. I can't imagine the difficulty of finding 20-30 different, independent, 1-month apartment stays directly with the apartment owners, dealing with security deposits and short-term leases, etc.
They're a directory/marketplace/availability clearinghouse. They're an intermediary. They're a payment processor. They provide ratings and reviews. They provide some miniscule level of support.
It might be the case that AirBnB is more bad than good, but I think it's at least a little unreasonable to suggest "you can just rent a regular apartment directly with the owner" for the digital nomad case.
It's easy enough to filter to self-catering apartments on booking.com. My partner and I generally stay self-catering wherever we go, we prefer the comfort of an apartment over the amenities that a hotel is able to provide.
Regardless of which platform I booked on, I'm the same tourist when I show up.
In a lot of countries the rental market is broken and prevents this. I've had this issue in the UK when I needed to move to London on very short notice after getting a job offer (and didn't have enough money saved up to afford a month's worth of hotel until I sort things out).
I had enough money to pay a deposit and a couple months worth of rent, so all of that paid upfront plus the employment contract should be enough to make most landlords happy.
The problem? The rental market around here seems monopolized by agencies and they all had referencing/application fees which means that even if I agree to pay the fee and take the risk of losing the fee if I get rejected I still wouldn't be able to get the flat quickly (my objective was to pay 2 months + deposit upfront and get the keys the same day). If I wanted to mitigate the risk of being rejected it would mean I need to apply to multiple properties at once, paying them a referencing fee to each (which I guess I'd lose if I back out even if I end up accepted).
Airbnb took my money no questions asked and I had a place to sleep on the same day. I'm still in that place 3 years later (paying direct now obviously)! I hate Airbnb for other reasons, but there definitely is a need for a better short-term rental system.
As far as renting from a regular owner, I think the hard thing about that is discovery.
Just to name a few you can stay in aparthotels , a common thing in almost every country, or you can just rent a regular apartment directly with the owner, instead of doing it through Airbnb.
IMO Airbnb does more bad than good and transform centric areas of big cities in amusement park for the tourist.