As soon as you have someone in your party - even someone much lower level - the enemies get so much health and attack speed that it is zero fun to play with the slow drudge (even before having to boringly wait around for cooldowns to reset because ultimate is now needed for every mob).
Since blizzard have tried so hard to make this a multiplayer game, it seems counterintuitive to ruin it this way
Hi, this is the same mechanic from d3.
Enemies become boringly easy if they do not scale.
So, as the enemies DPS is based on the mob size, as a party of 3, all 3 kill 1 mob member. It dies faster than if you solo it. As they only get about 75% extra hp per person.
So, do not spread out and attack different targets, attack the same target and they melt.
We were all green once! 
I think you and blizzard are making assumptions here - that people at specific levels will always have the same DPS range and that people will only group with people at the same levels . Both assumptions are wrong, as they should be, otherwise you’re railroading what builds can be played - as many people have complained about.
Enemies become boringly easy if they do not scale.
Not true. You’re biased because of how you want to play. I would argue that most people who group for content in almost any game do it because they want to power through something easier, not find it even harder. The level scaling is a travesty
Not an assumption, its literally the point of the game’s mechanics.
You dont want to be a 30 year old police officer with a 10 year olds nerf gun.
make sure your gear is good, or turn down a tier until it is. But the loot drops are very good and keep you in power if you pick the right gear.
focus on armour, and raw damage so big 2 handed weapons and whatever has the highest armour and big buffs to armour or damage lik2 “+ crit dmage” “+overpower dmg” “+plus % increase armour”.
It just takes a small learning curve.
Again with the condescention
Stating facts is not condescending just because your ego has an issue. The facts are right here in the thread.
literally offering you free advice that has seen me clear the game 4 times with not 1 death… and you have an issue? 
Assuming everyone is new, needs to learn or has to share every view you have is bigoted and condescending. You’re toxic.
Made no such assumption, I assumed that YOU were new, because you don’t know the slow high damage vs. fast low damage attacks that is a mainstay of this gaming franchise.
Not agreeing isn’t the same as not knowing, you toxic shill. Get a life.
Back on topic… If you group, you ALL attack the same target and reduce the total incoming DPS faster than if solo. 
GLHF
That defeats the entire point of a dungeon mob killing game. The fun aspect of any Diablo game has always been being able to run through mobs. I get higher content equals harder mobs, but it should not require your full party to kill one basic mob. That removes the fun from the game and makes dungeons a dragged out mess. Your whole argument is essentially “Get Gud” but people like you literally try to glance over what could be an actual scaling issue that needs fixed because you think the way you play is the only way.
I agree with this, aldo the increase of mobs HP isnt the problem, their damage also increases… or thats how i feel it… which is not ok, we as group arent more resistant.
Just leave it like in WOW… we all go group for faster / easier.