It's because of the administrative burden of maintaining a corporation not being worth it if you buy a single property (and the cost as well but that's not significant).

This is one reason why I posed the question.  

This includes tenant screening, writing leases if you don't hire a PM, managing rent payment systems, filing as needed with the county/city, maintenance and upkeep and how to out-source jobs that you don't want to do or can't do, scheduling, maintaining income and expense records, and the list goes on.

Plus if you think about it if the property is maintained the price is likely not gonna go down and so you should take into account equity gained.

Does it cost a lot more to maintain a 2,500sf house in Palo Alto renting for $10k/month compared to a 2,500sf house in Elk Grove renting for $1,800/month?

They have the license, experience, and a reputation to maintain.

Maintaining momemtum is important, and though I don't want to wait for winter it may be wiser.

Building a quality trustworthy team is not always simple and it takes work to maintain the team (even local takes work to maintain a quality team).As for buying your primary residence I have two considerations: 1) how long do you plan to live in the area 2) how are the long term appreciation outlook (in LA the long-term appreciation outlook historically has been excellent). 

There is a paperwork trail that has to be maintained and depending on which direction you go, there are tax and foreclosure implications.

What kind of problems can they have if any as far as maintaining them.