The math of fantasy baseball doesn't cause me stress.
What causes me stress is having enough time to do a good job with it. Contrary to what you say, it takes more time than just the few minutes each day to set your lineup. Just setting your lineup takes more than just a few minutes each day. That doesn't include the other stuff you have to do. Sure, you could get by with the bare minimum of just setting your lineup daily, but that's not likely to win you a championship.
For someone who is not working, that might not be an issue. For someone who is working and can't access these sites at work, then has to come home and take care of her family and her home, it is.