Why do car wiper blades have to be replaced in spring and autumn?

I think it may be because the rubber of wiper blades ages quickly after exposure to the sun in summer and low temperature in winter, but there is no sign that it will be replaced in these two seasons.

Under normal circumstances, it is replaced once a year, but if you encounter extreme weather, or if you have been cross-country in mud or something. The wiper blade is hung with fuzzy stripes, indicating that it needs to be replaced.