It's always had completely disporpotional coverage to other festivals/events (e.g. https://www.theguardian.com/media/2014/jun/06/bbc-staff-glastonbury-world-cup-brazil-2014), due to being a favourite of the higher ups in the BBC.
The visibility provided to the "general public" is unmatched. It has a huge impact on the number of Instagram influencer/non-traditional festival goer types applying for tickets.
What is true is that it's now a symbiotic relationship, for a better or worse - and claims that the BBC has either ruined the festival or kept it alive are probably hyperbole on both sides.