There's no doubt that writers should carry some sort of notebook with them at all times. Ideas for small posts or large are easily forgotten. I find some of them, if they're connected to something else I'm doing, will come back to mind – usually when I don't have a pad and pencil – but some just get lost forever. And ideas are too precious to lose.
I've kept a notebook in the past, but it's always a bit of an issue, and you always think – 'I'll remember that.' But you don't. And it gets worse with age. I can't even remember what I've gone into another room for sometimes, so trying to remember fragile things like ideas is tricky.
Writers should never struggle with writer's block, really, if they keep a notebook. But even without one there are plenty of ways to get the juices going. Read a newspaper, read anything in fact. Go through old notebooks (you must have some somewhere. I've got a box of them.) Surf the Net, but don't get sidetracked from your purpose. Read some other blogs, especially those you don't normally read. Look around your house: does anything annoy you about it, or inspire you?
I do understand that writer's block is a real thing, especially if you're a fiction writer. But the best book I ever read on the subject was by Peter Elbow, who advised just writing, even if it what you wrote was arrant rubbish. The fact of writing gets things moving in the brain and the imagination, and often something of value sparks up, and you find you're away.
Writer's block is more often writer's refusal to start writing, a putting off of the task in hand, since writing is work, and requires discipline and organisation, in spite of what the movies show.