Depends on what you use. Cross Country have much less compromise than enduros. On these, descent is the priority though, that's why you get slacker and slacker frames every year, heavy suspension systems and large tires that weigh the same as a dead elephant. The best sign that they're getting closer is that I'm feeling fine with going to the bike park in Whistler with my enduro, which I'd never have tried 10y ago.

Of course going up is always important and all these are not an entire sacrifice, powertrains are much better than they used to, locking sus actually works, and don't get me started with droppers!

But try to go up on a light hardtail retrobike sometimes, and then down. These were optimized for ups