Because they can, of course, the long thin stuff had wedged itself into the access plug for the coin trap so it wouldn’t come out when the machine decided it wasn’t happy with the lack of flow through the pump.
It therefore became necessary to drag the machine out so I could remove the top, control panel and front to get a the trap from the inside and pull all the crap out that way.
If I ever design a washing machine, it’s going to have a “crap trap” with separate access to enable easy recovery from such a situation.