Yep its just that easy! Figure out how much your roof weighs, buy some 2x4's or whatever Home Depot tells you will work, jack it up, cut it out, slap it in, and presto! do a little drywall. "Anybody could do it, go for it!" says a bunch of people that have no accountability.
You also have to consider snow loads, the length you are spanning, what the new beam/ header will bear on, what is size beam is underneath you supporting the current wall and whether or not it can handle the new point loads you are putting on it, how many stories is your home? Is there an upstairs and a roof bearing on it? Plus, if St. Louis County finds out you are doing this with out a permit in the wake of an earthquake they will be up your ***. Oh yea, worst case scenario your house does fall down and you didn't have a licensed and insured contractor, the insurance company has no one to go after so they dont pay out. I'm all for DIY when its something you have business doing yourself, but because you are on RC asking this I assumed you wanted input. What do I know, I only do this for a living. Im no Professor of Hardcore or LEO though.
Now, 8-10' is not that big of a deal, it just ****es me off when people spout off when they dont know what they are talking about. The moron that owned my house before me cut an opening in a loadbearing wall to make an opening for a skylight. Being that he was an idiot he didnt do it properly now the ceiling sags about 1" next to the skylight.