Yes because if punters are literally unable to get into see a band that was one of the deciding factors for them buying a ticket there going to be less inclined to turn up in future years when they realise they're playing the tent again. As mentioned Shikari were doing a tour of smaller venues than they'd normally play - hence the avalanche tent. If they come back high up on 2nd stage has to be where they go at least - they were playing against Slayer and Tool for a part of their set and the tent was still overcrowded with people packing in the grass down the side of it to try and watch. They might not have cared too much about tent overcrowding in 2019 but given a few high profile events in recent years they may well now.
Yup, would be insanity to but them on 3rd.