There is always a good reason for everything.
I think everyone should know that by know.
HVAC professionals would not just tell you that your HVAC system air filter needed to be changed for no reason. Air filters can become entirely so clogged. In fact they collect so much dust and dirt in the matter of only a month. Some people have so much dirt and dust collect that they need to change the air filter every month. Some people only change it every six months. However, you need to know your home and where you live. If you do not change the air filter often, there are some things that could happen to your home. The air quality in your home goes down. The dirt and dust could start to travel through as it gets pushed right through the filter by the strong air being pushed through. The HVAC system could stop working altogether. If the HVAC air filter does not work, the system could have an automatic shut off in which it will not operate. Only some systems are able to do this though. If you do not have an automatic shut off, then you could potentially start a fire within your system. The dirt and dust could become so warm from trying to push through the warm air in the filter that it starts on fire. So, in no way is having a clogged air filter a good idea. Make sure to change your air filter on a regular basis. I promise that they are not lying to you. It is all for something.