There are lots of different things going on when people speak- their accent, specific words you are unsure of, the volume, to what extent they move their mouth, gestures: all of this is communication.
I'm a lecturer, and it's very important to be able to communicate with students, many of whom have English as a second or third language themselves. I have one colleague who students complain about a lot as he not only has a very strong accent, he speaks in quite a chaotic rambling way, and they can't pin down what he's saying. He also is a poor communicator in terms of written materials, and preparing things in advance which would help hugely. We have to provide all our materials 24 hours in advance so that if students who are slow processors, dyslexic, have hearing or sight issues or otherwise can't follow along can understand what's going on. It's also very effective to gather information in more than one format, whether or not you have difficulties, as it reinforces the points.
There is one podcaster I can't listen to even though I love her content (financial advice)- I spend the whole time straining to hear and catching up about 2 seconds after she's said something.
I think the NHS doesn't prioritise communication at all, often consultants just speak, the words are lost, no-one can remember things at an emotional time. I take notes on everything that's said, the exact words, and just ask them to repeat things if I don't get them. I don't care if I look a bit simple, it's not possible to just memorize what people say if you are stressed.