Maxperson
Morkus from Orkus
So here are some posts of people making those claims.But why do you ALWAYS come back to that claim?
Other posters have proposed other metrics by which wizards are overpowered. Such as they can do their jobs well and still have a bunch of spell slots left over. Such as that compared to fighters, they can have a strong contribution across three pillars without being bad at any. Such as the fact that saying 6-8 combat encounters is not really a balancing factor since even WotC doesn’t follow it.
It also isn’t a claim that anyone made. It’s a conflation of several different claims.
- Wizards have the resources to overshadow other characters (not all other characters at the same time);
- A Wizard can be specced to replace virtually any role (except clerics) and still have the spell slots to do other stuff.
D&D 5E - Are Wizards really all that? - claiming that the wizard can do 7 roles well
"If the wizard is doing almost everything, he's still mediocre in combat.That 9 Roles.
Imagine if someone takes 2 roles off his hands. The Wizard is suddenly doing 7 Role well."

D&D 5E - Are Wizards really all that?
The Wizard isn't really All That The Wizard just has All That The two statements are different. If you look at the Party roles: Damage, Defender, Healer, Support, Control, Explorer, Lockpick, Sage, Scout, Utility, and Face. There are only 2 ahigh level wizard can't do: Defender and Healer...

Same person trying to demonstrate doing 7 roles well simultaneously.
"A 15th level wizard has 20 spell prepared, 4/3/3/3/2/1/1/1 slots, 5 cantrips, recovers 7 levels of slots, has a ritual book, some magic items, and has a subclass.
Only combat roles are resource intensive and the wizard is bad at 2 of them. Devoting a 2 cantrips and a few slots to Damage, A few to Control, and a few to Support still leaves you with 20-40% of your slots to Explorer, Lockpick, Sage, Scout, Utility, and Face."

D&D 5E - Are Wizards really all that?
I don't agree. Each class does it's primary function better than the wizard can possibly do it. In football each position has a unique skillset, but there is some overlap. Tight Ends and Running Backs both block a lot. Both catch the ball, but TEs do it better, but not as good as the WR who...

Different person saying the wizard can do 2-4 PC roles at once.
"At high levels they can be 2-4 men on the team."

D&D 5E - Are Wizards really all that?
I don't agree. Each class does it's primary function better than the wizard can possibly do it. In football each position has a unique skillset, but there is some overlap. Tight Ends and Running Backs both block a lot. Both catch the ball, but TEs do it better, but not as good as the WR who...

Yet a third person saying that the only role the wizard can't do simultaneously is healer.
"The only role it can't fill simultaneously on the team is healer, a la a cleric who might use healing during combat, which as everyone knows is sub optimal... But since every character has the ability to heal with a short rest or heal everything on a long rest, its actually a rather unnecessary "role"."