That's not the issue at hand. The issue is that there's no reason for anyone other than the wizard, or possibly rogue, to worry about those things.If you consider arcana, history, investigation, nature and religion dump skill, yes int is a dump stat.
If appraising an item, building a disguise, understanding a complex or crypt map is also dump skill maybe you're playing the wrong game.
That's not the issue at hand. The issue is that there's no reason for anyone other than the wizard, or possibly rogue, to worry about those things.
If the fighter and cleric and ranger all dump Intelligence as low as possible, then they can invest in other stats that will keep them (and everyone else) alive. As it stands, investing in Intelligence is just more likely to get you killed.
It seems to be pretty commonly held that Int is a bit too much of a dump stat in 5e.
Yes, that is a similar issue which also exists. Both Intelligence and Charisma suffer from the problem that they give very little to any class that isn't based around it, where every other stat has something that you'll really miss if you dump it. Even Strength lets you carry more stuff.You can also state that charisma is a dump stat for most class that don't use it in combat(sorcerer warlock pal bard). Except rare save like banishment and possession charisma is no use in combat.