I was inspired by a thread about chest hair when I noticed that a few guys mentioned shaving their armpits. I am a fairly hairy guy myself (though not back hair) and have been doing this for about 20 years (am 44). It is now a once-a-week SOP. I started doing this because I have relatively hairy armpits, and antiperspirant would never really get the job done for a long enough period of time. By the end of the day, I was a little too ripe. Plus, the hairs would stick together and pull when I moved. Very annoying.
FWIW, I otherwise like body hair on men. Just not pit hair. For those contemplating this, I have to say don’t worry too much about itching. It feels a little odd the first time, then when you get used to it it becomes second nature. For those concerned about appearing effeminate, don’t worry. It’s actually fairly difficult to notice.