Having recently been going through a huge mound of donations then the Op is wrong.
Yes, it would be much better in a lot of ways if everyone who gave a bag of stuff gave £5, but the reality is that you get fairly little that way. People are (naturally) suspicious of giving money and also people may be happy to give the sleeping bag that was bought for DofE ten years ago and used once, cost of £30, but don't have £30 spare to give.
I would give a plea that if you are in the situation that you want to give and are happy to give money, do some research for the charity you want to support and find somewhere where you are happy your money will be used wisely. But if you want to give item, look at what they're asking for and keep within those bounds. If you're unsure then ask. They'll happily tell you whether they will send over a couple of teddies. Let them make the decision not you. It's not personal, it's practical.
When you hand your bag of worn pyjamas over to the people who have asked for good quality coats only, you need to realise that, firstly, you're by no means the only one, so it's not a case of just your little bag. Secondly the area it's stored in may be limited so by giving that bag they may be forced to turn away a more useful donation. But also, if you are sending stuff out to a disaster zone, it costs to send things. They're not going to send a lovely pair of high heels when they can send something far more essential for life. Give the high heels to a charity shop where they can get money for it, or put them on marketplace and donate the money yourself.
If they say that they'll take rags and get money for them, that's a different matter.
It is amazing how people give in such circumstances. We were overwhelmed with the amount people had brought.
There were some things that we knew couldn't be sent over due to weight or wouldn't get used, but were sensible thoughts. We made sure they went to places that would get used.
But honestly, who thinks that Turkey needs a sausage dog draught excluder or two copies of "letter A" Encyclopedia Britanica?