Yeah per se if someone gives invitation letter but there would be no proof if that person is involved or not, coz while applying my mom’s visa I just wrote a letter on word and uploaded.It can have longterm consequences especially if the immigration fraud is ever discovered. If you invite people who then try to remain in Canada to work there may be further scrutiny on future visitors you invite because of concern they mayalso not be genuine visitors and are also trying to come to work .
if someone wants to write a fake invitation letter its just matter of getting their personal info right.