There are bands who write and perform 'songs', and there are bands that 'play music'. Phish is the later type, and it does take considerably greater skill to do so. That doesn't always mean the former type aren't good musicians. Sometimes they take the former approach because, well, it pays a lot more potentially, and most likely the groupies are a lot younger and hotter on average. And there are (or were) bands that do both together. Bands like Rush and Yes are examples of a band who composed songs and performed them for the most part as composed, but doing so required enormous musicianship. But I don't think there's anything like them close to the mainstream today? For that matter is there any non-song oriented band close to the mainstream at all today? The last decade has been about an ever shrinking level of musicianship, in favor of hacking and editing in the computer generally, at least in the mainstream. Bands like Coldplay are now pretty old school in comparison.