"ask your doctor" is more widespread than tthat. if you look up any diet or exercise advice, there's always an "ask your doctor before starting any new exercise program".

i'm not going to call my doctor to ask "is it okay if I try doing kettlebell squats?"

Yes, I totally got out of context and said something a bit senseless.

But also, maybe calling your doctor would be wise (eg if you have back problems) before you start doing kettlebell squats.

I'd say that the audience for a lot of health related content skews towards people who should probably be seeing a doctor anyway.

The cynic in me also thinks some of the "ask your doctor" statements are just slapped on to artificially give credence to whatever the article is talking about (eg "this is serious exercise/diet/etc).

Edit: I guess what I meant is: I don't think it's just "liability", but genuine advice/best practice/wisdom for a sizable chunk of audiences.