You mean normal riding? Meaning anything off-road? For me that defines ‘mountain biking’ generally. No need for sub-categories, no need for a particular ‘weapon’. Ride anything on the one bike, any trail, anywhere. Moors, field edges, trail centres, woods, mountains. Uphill or down, fast or bimbling. Any combination of that in one ride. It is possible to ride on the flat quickly and smash decents, without calling it En-XC-duro, or caring what it’s called.
None of it needs categorising based on perceived speed, trail difficulty, bike type, geology, clothing, whatever. Thinking too much about all this stuff is pretty joyless, and a sign of spending too long thinking about it indoors and caring what the internet says.
OK, rant over 🙂