The above phrase, and those similar to it, really piss me off. Usually X and Y are quite different things, and the assumption that the ability to do X makes Y possible too, is so simplistic and just plain inaccurate. This kind of belief seems to form the basis of disability assessments, and ignores how different situations lead to different responses and abilities from the person (trying to) cope with them.
Here's a really obvious example : "If you can type on social media, then you can work". Yes, typing is a task done in many jobs, but being able to type a few words in response to acquaintances online isn't the same as concentrating for hours on tasks involving typing, and meeting the targets that employees are often set. In such a job, it's likely you'll need to communicate with other members of staff, fetch and carry things, attend meetings, and use the phone amongst other tasks. So no. It's not just typing.
Another one would be the assumption that, if you can cope with one group situation, you can cope with every group situation. Again, other things need to be considered. How big is the group? How far away is the session? Can the person always get transport there/if they need someone to accompany them? Is the group situation a formal or informal one? Can the person leave if/when they need? What facilities are there (toilets, drinks facilities, disabled facilities etc).
I have various anxiety disorders that can severely affect what I'm able to do. Different environments and situations can have a big impact on me as well. On a good day, I may be able to meet a couple of friends in town for coffee (as long as I can get transport from my dad or one of my friends). It has to be close friends who understand that I struggle, and are patient with me. They have to know that I need to be in the quieter areas of town, have places to sit down, and they need to be ok with it if I'm struggling too much and need to go home.
This doesn't mean I could cope with *any* group situation. A while back, I was referred to the Expert Patients Programme to help me manage the combination of mental and physical problems that I have. The content of the programme sounded interesting, and at the time I was feeling a bit lost as to how to cope with everything. Unfortunately, the thing that stopped me taking part was the fact that it was a group programme. I knew that everyone there would be in a similar boat to me, and that the staff would be understanding if I needed to leave, but this didn't stop me from being far too anxious to go.
I understand the need to apply things to different situations, but there are so many other things to consider. For lack of better phrasing, if someone can do X, then that only shows that they can do X. Y may be impossible for them. Please believe us, even if you can't fully understand the complexities of our health problems.