I don’t think this is true at all. I used to work with county councillors. Most of them wore different colours to me, but almost all of them were good people trying to do the best for their constituents in difficult circumstances. Two of them have gone on to be MPs and they work hard, hold surgeries frequently, turn up to open events and do speeches at local conferences. They are contactable through their social media profiles, and they have set up task forces to try and improve issues of particular importance to our area. They represent us and speak about us frequently in parliament.
So yes, there are some who are there for the wrong reasons, and we can point to the greedy, the lazy, the sleazy, and the stupid, because they keep putting their feet in it, but most are decent.
The one thing I would change about the electoral system is that the MP has to have lived or worked in the area in which they’re standing for a minimum of 4 years, and they have to have been a councillor in their local parish, town, district/borough, or county council so they have a real, deep, and comprehensive understanding of the issues facing their local communities. I don’t like that people can be parachuted into a constituency when they have no link to it or understanding of it. It also means that their constituents know them and can make an informed decision on their suitability for higher office.