It is more of a professional courtesy. When addressing actors/dancers/etc, we refrain from calling them "luvvies", "turns", "twirlies" or any of the more "inappropriate" names (at least to their faces), and expect the same in return.
"Techie" tends to be used to describe 14 year old boys who think they know it all, know they know more than you, and believe that their school needs to buy some movers and a nexo line array because they R0xorZ. These "techies" can usually be identified by the fact that they come up and great you saying "Hey, I am xyz, the schools techie." when you rock up to help them with a show. They can be further identified by the fact that they will talk pure bull, as they tell you that your console is crap compared to the ZXY Light Maker II they read about last week in the local "DJ Times" magazine. The final identifying mark is that you will ask them to please not eat and drink in the Bio box, and yet you will come up during the middle of the show, and find coke all over your desk... So yes, many techs find "techie" to be a degrading term
However, that is going far, far off topic.