This business of hardtails being "better" on particular types of terrain or whatever is bobbins.
A hardtail has a couple of advantages over a full sus bike:
– the frame is cheaper (meaning the cost of the bike is less, or for a given cost the components can be better);
– for a given cost, it is possible to create a hardtail frame (and probably therefore bike) that is lighter than a full sus.
– there is less to wear out/go wrong becauser the frame does not have any moving parts.
After that, you're just looking at whether you can get away with riding a hardtail on the terrain or for the type of riding (you mostly can) or whether rider ability is a mcuh more signifcant factor in speed, comfort or enjoyment than the typre of bike (it mostly is).
The only "advantages" of my hardtail over a full sus of similar quality are:
– it saved me about £500
– it will never need its bearings replaced
The disadvantages (basically, it lacks an efficient rear-wheel suspension system!) are not sufficiently significant to make me value the suspension more than my £500. But the hardtail is not in any meaningful sense better.
😀