I think the problem you are talking about,could be coming from people who haven't validated a radar/tower rating,or don't even have one.
There are three distinct issues here, which in the UK are NATS issues, and not a problem for others.
The first relates to the gradual atrophying of skills when APS is separated from TWR and the controllers doing the respective jobs finally become disconnected with the other ~ as is happening across the board at the UK's London airports. The situation is exacerbated by the move even further away i.e. to Swanwick which makes the logistics of liaison visits difficult.
The second relates to the so-called 'skill specialisation' whereby trainees coming out of the 'college' training regime no longer have APS
and TWR ratings and so have minimal understanding of each other's tasks and operating environment.
The third relates to the 'streamlined' training that's now fashionable whereby trainees no longer spend several weeks at centres, approach units or towers as part of their basic training.
The only demonstrable advantage that this policy has is a financial one (and has been said earlier) a contractual one; operationally, the pros and cons are almost impossible to objectively determine.