It’s something I keep an eye on, and something I try not to think about when on the trails. I live near Bedgebury Forest, which has a relatively tame red route. I do it regularly on my Pace RC200, Orange P7 single speed and modern Planet X Ti gravel bike. All can handle it fine — I’m not as fast as a good chunk of the people on modern kit on the downhills, but tend to be faster up hill. I also avoid the big jumps or anything else that might stress the bike too much. Let’s face it, these sorts of bike parks didn’t really exist in the early 90s (North Shore excepted!), so most bikes weren’t designed for that sort of punishment.
With the Pace, I tend to keep a bit of an eye on the Ringlé stem (already cracked a face plate), and the lovely billet machined (not forged) Middleburn cranks give me some conniptions. Oh, and the clamp on my beautiful X-Lite Pro stubbies have cracked
I haven’t ridden much in the way of modern MTBs. Most recent experience was out in Zimbabwe where I borrowed a modern Rocky Mountain. Riding around amongst zebras and giraffes was amazing, but the bike itself was totally anodyne. It just rode through everything. No thinking or skill required. I think I enjoy the skill rather than the out and out speed, so reckon I’ll stick to retro.
On the ‘well maintained’ point: well maintained usually means you’re also keeping an eye on your components. I didn’t faceplant honking on my bar ends out on the trail because I noticed the start of a hairline crack while cleaning and inspecting all the parts. Hopefully the frame will last as long as I can cycle…