I think the scale of ppl who are on benefits / sick leave with MH problems creates resentment in those picking up the slack at work / paying into the system, which gives support to these cuts.
If people could get access to MH services in a timely manner, then a vast number of people would not have ended up so ill, and in need of benefits. Those services need to be accessible, and ongoing in some cases. Not just talking therapy for a couple of sessions, etc.