The suitability of terrain for a cycling discipline comes down to one thing: your skill level. If you're not experienced enough to handle the terrain, it's not suitable for you.
When it comes to assessing and preparing for different road surfaces, trail features, and environmental conditions, it's simple: do your research. Don't expect others to hold your hand through it. There are countless resources available online, including forums (like this one), blogs, and videos. Use them.
As for optimizing your bike setup, tire selection, and riding technique, that's on you too. I own high-end Zipp 303 wheels and a Cycleops Pro 3, and I can assure you, I didn't get here by relying on others. I put in the work to learn what works best for me and my bike.
And as for rough roads, gravel, singletrack, and high-altitude mountain passes, here's a pro tip: if you're not comfortable riding in those conditions, stick to smooth pavement. It's really not that complicated.
So, to sum up: assess your own skill level, do your research, and put in the work to optimize your setup and technique. And remember, nobody is good enough for me, so don't expect any special treatment.