I remember as a kid going to Karate class and before stepping onto the dojo floor, kicking off my flip-flops under a big sign that said leave your ego and shoes here.
It didnt mean much to me then, fast forward to when I taught from home, for a while between gyms in Durban, SA, we trained out of my garage and I had a sign there similar to the one in this article. It was an attempt at using humor to remind people to take their shoes off before stepping onto the mat.
For sure hygiene is a huge part of it, we roll around on those matts and would rather not have skin contact with whatever has collected on the sole of your shoe, but I still often think back to the sign at my old Karate class.

Learning to leave your ego off the mat affetcs you greatly in your jiu-jitsu life. There are two critical points that I feel it probably does more so (at least from my experience) and that is at white belt and then again at black belt.
A major reason Ive experienced with students quitting early on in Jiu-jitsu, in my opinion is ego. You have to be prepared to tap to training partners who are smaller, weaker, older than you or who you may feel are just plain inferior to you.
We have to learn to put our ego to rest.
Stay open to learning, and keep in mind how often we derive more from defeat than victory.
Just get out there having fun, enjoy your time on the mat, and not try to rip it up or impress anyone. Just roll for the fun of rolling, treat your training partners with the same amount of respect you'd like to be treated with. You will improve if you train hard and are consistent, but leave that ego off the mat.

Now imagine if everyone carried that attitude with them off the mat with them into their day to day lives.