Alton Towers is not busy. Busier than it was in 2016 or 2017, but not busy.
The problems we have here are that due to ride reliability being the worst I can ever recall, queues on rides that are open are exacerbated.
For example: take Th13teen. This ride can, in theory, achieve 1,400pph. With the new baggage situation, it's probably down to around 1,100. But even then, not bad. However, add in the sheer volume of Wicker Man fastracks being dished out due to that ride being closed for whatever reason - and everyone makes a route straight to Th13teen. Also, because Th13teen opens late (11am), and there are frequent breakdowns, these people are then shoved through the ride in less hours than a full day. This means the main queue time is horrendous.
We also need to remember that since 2015, the park has seen cut after cut. In 2016 and 2017, the park managed because guest numbers were stubbornly low post-incident. However, this year we're seeing higher numbers. Not the numbers we'd have seen a typically good year (e.g. 2010) - but higher numbers nonetheless. And due to the cuts... the park simply cannot cope.
They need more money, more staff and more support rides because Alton Towers simply isn't good enough this season. And they know it. I bet they wish they still had Ripsaw now!
On a side note, VR should be removed off Galactica immediately to boost ride capacity per hour and the staff that are then not needed can be redistributed on other rides/areas.