I'm a buyer and seller.
There's absolutely nothing wrong with watching an item, whether you intend to buy it or not. There's clearly a reason they are watching it. Some are interested in an item and deliberating whether or not they can justify spending the money (even on small things) or whether they like the item enough to actually buy it, or if there's a cheaper alternative before choosing that one, waiting til they get paid and hoping it doesn't sell till then etc
Watching doesn't mean you've made some kind of pre-sale. It's exactly like going in a store, browsing, seeing something you like then keeping it in your memory as something you're considering buying. It's easy to lose things on eBay, hence the watch function.
If I knew a seller had an attitude like that I wouldn't be watching their items and they could potentially miss out on a sale. It's like being mad at a person because they refuse to give you their money and take your items. Ridiculous.
Also yes things do happen in life and mistakes are made. If a person is genuine and apologetic I have no issue with that. Not everyone is a CF you know.
People who are rude via messages, who lie about not receiving items, who try to take the absolute piss (can you halve the price of your item and also courier it to me for free even though it's collection only) who complain about postage after buying...these are the kind to get annoyed at. But sometimes genuine mistakes do happen, and life happens too. I don't make eBay priority when one of my family is ill or there's an emergency. I'm not a big branded business with employees to stand in for me.
I just had a message from someone who has been ill and not yet posted items I bought last week (I actually know from the item they are being truthful about their illness) they were sincerely apologetic and honest. Did I find it annoying and feel infuriated? Of course not, I was understanding. I'm a human being too. It's only eBay (they were not a big business seller either).
If you start seeing everybody you have an issue with on eBay as an arsehole then chances are it's not always them. I agree that some people take the piss and it's wrong, but you can't get infuriated over every single thing, you have to make allowances sometimes.
I do agree that there's too much protection for buyers compared to sellers - having to refund over a signed item because a signature 'isn't clear' is absolutely out of order. Luckily that's the first time I've ever heard of that. When I've challenged with a signature I've always won.