Dump stats are common for both mechanical and roleplay reasons. Personally I try to not dump a stat unless I have a roleplay reason for it.
For example, both of my Githyanki characters in BG3 dumped CHA because they're stand-offish, rude people who don't care about making friends. Meanwhile my dwarf ranger dumped CHA because he's not used to being around people anymore after spending years alone living off the land after his home was destroyed.
Also, since I see a lot of people here also have a hard time dumping INT; don't think of it as an actual intelligence stat. Think of it as an education stat.
Look at the skills it governs. Most of it is about what your character knows with only investigation involving actual critical thinking. The stat that governs how much of an idiot your character is is actually WIS, which governs the ability to notice critical details and determine if someone is lying to you or not. Which are traits I'd personally associate with actually being intelligent rather than just being well learned.
As an example: I had a Lizardfolk druid who dumped INT and CHA. His backstory was that his tribe got taken over by a dragon and only he was able to realize that the dragon was just using them for cannon fodder. So he left his tribe to find a way to convince his people of the truth. Either evidence of the dragon's nature or greater personal power so his words carried more weight with his tribe.
He had low INT because he was raised by a tribal community in a swamp and simply never received a real education. He had low CHA because he was bad at public speaking and him not being good at convincing others of the truth was a big part of his backstory.
But he had high WIS with proficiency in Insight because he was very good at noticing deception, playing into his interaction with the dragon. He was incredibly perceptive and often warned the party of hidden traps, and his skill in survival made him able to tell what berries were good to eat and what weren't, help with tracking enemies, and his modest skill in medicine made him quite good with dealing with poisons and diagnosing illnesses in others.
Was my druid stupid? I don't think so. I feel like if you met someone in real life with similar qualities you'd consider him quite smart, just not interested in having a wide breadth of accumulated knowledge from academia.
Basically, there's more to being smart than just knowing trivia. A truly intelligent character can be made with high INT or high WIS. I'd even argue a high CHA character to be intelligent in their own way.
You only get a genuinely dumb character when you dump INT, WIS, and CHA all at once.
