I think the point is the DM still decides to use it or not.
Doesn't really matter imho as long as it's consistent.
WotC RPG police won't be coming around and to your place and beat you over the head with the errata book.
Generally I don't go out of my way to follow errata but I do tend to use updates in books I own.
That's beside the point, however. The errata and sage advice are the official updates and rulings. That's going to be the default when different groups from different tables share a discussion because they are the official standpoint.
I don't always follow them either but I cannot present the rules I use as the rules over those ones.
Not at all but there's better combat classes and better support classes and I would argue both eg clerics
Present the arguments instead of general statements if you would make that argument. ;-)
Bards are an excellent support class and we already touched on those differences. Clerics have more spell prep and similar AC to artificers but still lack the infusions, SSI, flash of genius, or tool expertise.
The bottom line is spell progression is traded off for infusions and infusions don't suck.
Mending should be on their known cantrips anyways. Artificers can change a cantrip when they level up, too.
Also, if they want to get more cantrips, there are a ton of ways to do so. (High Elf, Magic Initiate (Wizard), Artificer Initiate, etc.)
Cannith us a decent race choice to pick it up with the mark of making.
How many of the people IN THIS DISCUSSION are at your table?
You are talking with people you aren't playing with. Learn how to deal with that courteously, and without the assumption that the world must subscribe to your particular preferred documents.
I'm going to reverse that. How many people in this discussion are at your table?
The concern I had was the apparent denial of the official material as official because DM's are not required to follow it.
The default rules are going to be the errata and the default rulings are going to be the sage advice. None of us is required to follow it, and none of us should be forcing it on others; but we should be acknowledging it and there's nothing wrong with explaining it.
Explaining the rules isn't forcing them anymore than a DM expressing what he/she/they do and why.
I'm dropping that particular argument and this point. It still seems to be a tangent to the artificer topic.