I am the fly in the ointment. No, I don't just throw my vent open and leave it. It makes you lose more smoke requiring more chips/chunks/pellets. It causes the electronic heat to cycle more often placing more stress on the electrical parts and we all know where those electrical parts came from...... stress can't be good.
I use my vent. I regulate my vent. It makes my MES work more efficiently there by making your smoker last longer, operate less expensively, that's a good thing.
I open it full to light my auxiliary smoke generator, it pulls a draft so your pellets can smolder. IF you use chips as the unit is intended, you don't need that much draft and you regulate the amount of smoldering the chips do with it.
If you have wetted meats from brining/curing or meats with added water like sausages, you use the vent open to help move out that humid heat and dry the meats. Then again you regulate it to obtain max efficiency in the smoker. I have used the old ventless electric smokers since back in the 80s where you put in chips and used High electric heat to smoke them before the lack of air puts them out. It works fine as long as you understand the method and don't try opening the pit to baste sauce turn mop or spritz. That is NOT how an electric is meant to work.
People will tell you its stale smoke, as opposed to what? Fresh smoke? As long as you don't over smoke or use green wood or basically try to use the pit as its not intended it works great. You really don't want smoke you want flavored heat, that's why we all talk about the thin blue smoke.
BUT the great thing about smoking is we all have our ideas and everyone is also entitled to their own. MY suggestion is try it for yourself. Throw it open once, next time try to regulate it maybe 1/2 way and see what you think.
When I chip smoke in my MES30, I usually wait to put in my first load of chips till after the first hour, then maybe 2, 3 at most reloads at a min. of 1 hour intervals. That should give you easily 5+ hours of smoking. If the vent is full open you'll get a little over three I believe. But since you are only really looking for smoke from the 100 to 140 degree internal temperature anyway it is much better than you need.
Try it and see what you think.