See that's what a lot of people like you aren't taking in account:
Yeah, the integration tools can be substituted with other stuff, but if you don't want to bother yourself about it and have it come out of the box, it works pretty much flawlessly with Apple. Write down a note on my phone, finish it after work on my iMac, or leave myself a post-it note on my iPad from my iMac to remember to do shit when I'm back in class, all of my shit gets automatically backed up to iCloud so whatever I'm working on I just pick any of them and can keep working. The whole suite is like that, literal plug'n'play instead of having to deal with various websites and setting up other apps.
A lot of people would rather not deal with the headache of having to do all of that shit. On top of it you don't have to worry about firewalls, viruses, etc... Yes yes I know they exist but they are still something you don't have to worry about unless you fuck outside of the ecosystem, and 99% of people have no reason to.
Take that in account, and keep in mind that a lot of the people who can afford to spend that kind of money on electronics tend to be older, in their 40s and 50s or plus. I have my mother who's about to retire, got her an iPad which she loves and doesn't have the same problems she does with her windows laptop, and even my grandmother can pick up her iPad and knows how to deal with at shit and she's over 90 and the biggest piece of electronics she's used before is basically the tv remote (and grandma ain't fucking with anything except on/off changing channels and volume).
Add that on top of the fact that those are durable and are really unlikely to shit the bed on you and that it's quite common for people to keep using a mac for 7+ years or so. Between ease of use, quality, integration and the fact you won't have to do any maintenance, it justifies the price tag for a whole lot of people who can simply afford it. Why not pay $500-$1000 bucks extra if you're going to avoid having to deal with a lot of shit you don't want to?