TurboTax is meant for an individual to file taxes for themselves and their family. Most families do not live in more than five states. Most only need to file one state. What happens is the people try to use it as professional tax perparers and start charging others to do their taxes, then using TurboTax to generate and e-file the returns.
To discourage that, the IRS limits the number of e-files an individual can send to five. With online TurboTax, it does not matter, because you can only use an account for one person. With desktop, it there were no limits on number of states downloadable and on number of e-files allowed, then a person could use it to prepare thousands of returns. They would not be able to be responsible for everything that they were filing.
With professional software you can have ll the states and unlimited e-filing, but the IRS is assuming you know what you are doing and able to take responsibility for preparing many returns.
