Apple's vintage clock starts when they stop selling something. They sold the 6s until 2018. They rarely sell MBPs for more than a year so usually in 7 years they're done.

I'm glad you're currently well to do and can afford all new shit for your kids. Some people can't and sometimes a repair is the only option. Is it worth making repair considerably harder for a few extra mm of thinness and less than a hundred grams of weight? I'd argue no. Compare the repair of a 2010 MBP with one from 2016 and then tell me the 2016 one is easy.