If you have a chronic health problem or a disability that affects your day to day ability to cope with the basics of living, then you should put in a claim. If you are fit and well, just be glad. I know I am.
That's probably why so many people put in claims for PIP that have no chance of success thereby clogging up the system for everyone.
Irrespective of whether a disability affects day to day ability and trying to cope with the basics of living if you don't manage to match exactly enough of the descriptors AND gain a minimum of 8 points for care or mobility then you will not get an award.
There are many sick and badly disabled people that life is almost impossible to cope with, but will not get a PIP award as they don't match the requisite descriptors.
On the other hand there are some that have 4 lots of aids that have some level of disability that help them cope which means they will get an award for those aids. Aids such as a walking stick, an aid to wash their body, a radiator to help them get up from sitting down, a sink that helps them get up off the toilet, a shoe horn to get their shoes on etc.