This is not exactly true ,is it? It certainly isn't true for all Chinese visa application centres. In the UK you can definitely obtain a travel visa all done by post. They ask for you to send a Royal Mail special delivery return envelope. This is safer than using any agent, who often use iffy couriers.

If you want to call yourself you will now need an appointment in London and return to pick up your passport the following day, since they have ended same day service as from 2009 or 2010, I forget which.

An agent will not deal with a family L visa for you, you will be required to attend in person.

Business visas, I'm not sure about.

My advice is though, do not rely on what agents tell you or what I tell you-all you need to do is access the website for the visa centre/embassy where you want to apply for your visa-it's all there. Don't use agents for anything if you can avoid it.

I don't know for sure but what's true for Chinese Visa Centres in UK is true for ones in USA.