You can learn a lot from free-rolls, sure you get the idiot all-ins at the start of the game, I am as guilty as the next guy, but in later stages when the game settles down players start to play better and more realistically as they would in a Buy-in game.
Playing free-rolls allows you to change gears when it comes down to the money bubble, because the game does change in how players proceed, also when you get down to lower numbers you will experience short table numbers and again have to change your playing style accordingly.
Finally reaching the final table, you will have to try and ladder up through the pay table, until eventually you reach heads-up play and either win or lose. All different aspects of the game can be experienced through playing Free-rolls, and the most important lesson I learned was How do you expect to win a buy-in game, if you cannot win a free-roll occasionally?
I have won a few over the years, cashed in many, but lost in thousands of them, I still enjoy playing free-rolls mainly because I cannot lose any money in them, and they are a great way of feeding my "Poker Adrenalin Rush" I have learned a lot through playing them, enough to start playing in Live games in Pub's, Club's and Casino's and hope one day when this Pandemic is History, "I will be Back!" (lol) playing live games again.
When the fun Stops, STOP!