Should MLB have nets all around the stadiums?

Add insult to injury...literally.

Man gets hit in the head with a foul ball then gives ball to woman in front of him. pic.twitter.com/8wWSgM60t1

— SportsTime Ohio (@SportsTimeOhio) August 30, 2018

From the NY POST.

A man in Cleveland took a foul ball to the head Wednesday night, but his finger-pointing didn’t skip a beat. Seated along the left-field line at an Indians game, the fan was drilled by a ball off the bat of Twins infielder Ehire Adrianza, then blamed the woman in front of him for not catching it.

Read more here. 

My question is, Why aren't there nets all around the ballpark? This could hurt someone really bad too, right? What about when folks walk down and block your sight lines in during at bats?