for the same reasons that it is not adviseable to use compressed air from your home compressor. the only thing you should be using to blow your pc out is compressed air from a can meant for this purpose.
reasons why not to use a compressor:
- there could be oil in the compressed air flow
- there could be particles in the airflow
- you could unintentionally charge the surfaces inside your pc case and then discharge them resulting in potential damage.
could you do it? why sure you can do it but realize that there is a larger risk of issues resulting from this over using canned dust spray. personally i will never risk my components this way.