I hate quintile mobility as a metric and don't think it should be used. Quintile mobility is zero sum. It's impossible for anyone to move up without someone els

I hate quintile mobility as a metric and don't think it should be used. Quintile mobility is zero sum. It's impossible for anyone to move up without someone else moving down. I don't want people in the upper middle quintile to go down. But I also want people in the lower quintiles to move up. To upper middle if not top. Neither wealth nor income is zero sum. Zero sum analyses are therefore not useful IMHO.