Hey Av you got your reply in while i was typing i guess. - There may be a good reason but ive not experienced anything bad to my knowledge so far . They are made for this sort of duty cycle imo coupled with the performance and price point makes it a winner for my needs
the only thing to watch for buying any pump is whether or not the impeller is magnetically driven. because if not the motor shaft goes through a bulkhead and also drives the impeller. there will be seals that will eventually wear out and could allow oil from the motor into the system.
some may have dry motors and will just fail without contaminating the system. i've used danner mag drive aquarium pumps for years and now these little magnetically driven eco pumps which have proven to be quite reliable.