"It seems such a bad idea to rely on a property management company" - I couldn't disagree more.
For one thing, you are assuming property management is easy, and you have all of the required knowledge, skills, and abilities to successfully navigate everything from privacy and fair housing laws, to unit turnovers, advertising, showing, screening, rent collections, accounting, evictions, and providing 24/7 maintenance.
Don't get me wrong: Self-managing is not a bad idea for your first few properties, and I highly recommend it for new investors. Otherwise you'll never appreciate how difficult it can be, or how easy a professional property manager makes it look.
You have to know a lot of stuff about a lot of stuff to be a great property manager (for an idea of the breadth and depth of knowledge required, check out the list of training videos at http://www.evicttv.com/all-vid... (no affiliation, just a great repository of PM info)).
If you do have the knowledge, skills, and abilities, that's great! But do you have the time? And is your time best spent on PM activities?
The other half of your argument relates to scalability, and is counterintuitive. Having effective property management in place is what can allow you to scale up, by spending your time building capital, researching markets, and buying more properties.
My argument for property management looks at two scenarios:
Investor A self manages, because he loves saving 10% of his rental income buy self-managing. He can manage 5 doors no problem. But 10 years down the line, he's now managing 15 doors by himself and has little time for anything else. This isn't scalable at all: He is no longer much of a real estate investor, he spends all of his time doing property management. He doesn't have the time to research markets, analyze properties, or grow his portfolio. He's working in his business, not on his business. But hey, he's saving 10% on management fees, which is great.
Investor B puts property management in place from day one, because her plan is to acquire 2-4 properties per year for the next decade, and she views property management fees as a wise investment in her time, which allows her to focus on implementing her strategy: researching markets, building partnerships, raising capital, and acquiring properties. Her property manager takes care of the tactics: everything from turning over vacant units, advertising and showing vacancies, tenant screenings and background/credit checks, rent collections, accounting, liability reduction, evictions, maintenance, and everything in between. 10 years down the line, she now owns 50 properties, which combined take her all of 5 hours per month to oversee. She easily has the capacity to acquire 50 more properties in the next decade, consolidate her portfolio though 1031 exchanges, or generate tax-free capital though strategic refinancing.
Which investor has a better strategy for building long term generational wealth?