FrogReaver
The most respectful and polite poster ever
I think it is more because the costs for dumping stats is rarely enforced IME unless the DM is a stickler for it. A lot of games hand-wave away encumbrance, so having a sorcerer with STR 8 is not a big deal. That character is not expected to do the heavy lifting and since DEX (Acrobatics) can be used in place of STR (Athletics) in most combat situations, it isn't a penalty there, either.
Most do use encumberance - it's just so hard to hit the limit in the default rules that it just seems like it's being ignored.
In a similar fashion, low INT and CHA also don't really affect much because most players play their characters as more intelligent and charismatic than the character should be. So, again unless the DM steps in and makes them play appropriately or use checks instead of role-play, there isn't much impact to the cost.
Valid Low Int playstyle - come to the same conclusions the intelligent character would come to for all the wrong reasons - at least until the big consequential moments occur and then your stupidly incorrect conclusion is wrong for all to see.
Valid Low Cha playstyle - You've almost got being charismatic down. You say mostly the right things but have a tendency to really mess up your charm in the big moments.
A player can play a PC with a low stat in lots of different ways. IMO DM's shouldn't be policing that. Instead give them the opportunity to fall flat on their face once in a while.
I am not saying their isn't a cost, just that I rarely see it have an impact to the point which having a dumped DEX, CON, or even WIS will have.
Nearly all classes need dex and con. Wisdom is a stat I've dumped many times. It rarely had an impact. I've dumped con before. It had an impact on me playing my rogue a lot more skiddish but that was all (behavior change only). I don't think it ever had an impact other than that - i mean my hp value showed low but tactically positioned myself to avoid most all damage anyways so not really much impact.
In fact, I think I've dumped nearly all stats before. I find dumping a stat tends to give my characters a more fun and memorable personality than not doing so. IMO stat dumping shouldn't be discouraged but instead encouraged.