Yes my mother does this.
But she uses the cheap thin bleach that costs about 20p from Asda - buys loads of it and leaves it to soak and then brushes it off with a hard bristled brush. Does help with the weeds too but might be more effective in addition to use something like a potato peeler to scrape out the weeds and then you can re-fill the joins with sand properly afterwards.
A power washer would do a better job and done once a year will really clean all paving greatly. You can get small ones as well as large ones. It will take the weeds right out of the cracks, roots and all.