It's basically their way of saying that they use such sub par construction that they probably would not even last a year if they were used year round. My guess is the root issue is they probably don't use UV resistant plastic so if it's exposed to sunlight in summer it will become brittle.
I would love if there was options of buying really high quality ones that are built to last and usable year round, as they have nice uses for general lighting. I guess addressable RGB LED light strips are better for that. I eventually want to play around with those for some permanent lighting.