You know, he's kind of got a point there.
I agree to a point. The point would be even more relevant if people only ever rode in one place but a lot of people don't and I guess the flexibility of having one bike that is as capable of doing Surrey Hills as it is La Flegere in Chamonix or Kind Scout in the Peak is quite appealing.
I've ridden extensively in the Surrey Hills on both my AM bike and my hardtail (as well as Wales, Chamonix, Peak, Lakes etc) and I have as much fun on both but for very different reasons but I've never felt that the 150mm bike was too much for any trail; it just allows me to ride a heck of a lot faster and I quite like that.
Besides, the surrey hills aren't quite as tame as everyone would like to think they are. There are some fairly steep sections, some steep tight turns, decent drops and some fairly big jumps – certainly there are more drops and jumps than I've come across in the Peak or Welsh trail centres.
All of that could easily be ridden on a HT by a capable rider (reference here to Jon Edwards on any one of his Cotics) but at the same time, go and try riding with someone like Howard or Jo from Pedal & Spoke. They will be on 34lb Nomads (until they get their Carbon ones 😉 ) and just try to stay with them going either up or down; those guys are blindingly fast and then look to see if they aren't having just as much fun as anyone else.