Yep, they "need" to replace the entire top case/keyboard to replace the battery. Just sent mine in for it, but not so annoying for me as it was a 5 year old one with nearly 1000 cycles. Interestingly I think they are going to airmail it! I wouldn't want to be the pilot.
This is what bothers me about Apple. Apple designates their computers obsolete after 7 years or so, after which, presumably, it's impossible to get an official replacement on what should be an easily replacement component which they themselves designate as "consumable". Their computers can, and do, last a lot longer than that.
It's no accident that it has been designed this way. They use dead and dying batteries and the high cost of replacement as a weapon to "encourage" you to upgrade. I have a 16" MBP so hopefully, if the next 16" maintains the same design, I've still got a good 7-8 years where it'll be possible to get a top case replacement, and I'll be selling long before that, but there's an issue of principle here that applies to all their other portable devices as well.
It sure was nice when you could replace the MacBook battery without even turning it off!