From the view of sat service corporations such as Voom, they are going to have a higher install success rate working with installers than allowing the end consumer install it. Many of us here have past experience with installs and can pull it off, but many folks who may think thec, can't. I can just imagine some of the nightmare calls Voom would get trying to help joe blow through his incompetence. I realize that some of the installers may be no better - but in general I think that the installers are much more qualified and have installed many more systems than you or I.
So - they have to choose between paying installers, or allowing end consumers to install and therefore have to hand hold many of them over the phone. With installers, at least they only have to deal with one person if there are problematic installers (Joe Harkins). With self-installers they have to deal with each one on an individual basis. Lastly, Voom may face more lawsuits with self installers - if joe blow electrocutes himself or falls off the roof he may sue Voom even if he may lose. Professional installers are bonded and insured. So - it's a trade between cost and risk - risk of lawsuit, risk of losing a customer because they can't install properly, etc. Tough decision.
Maybe we would have fewer problems with professional installers if they provided them with more up-to-date information.