Maybe I'm crazy but I'm genuinely curious, what's the point of these kinds of builds? I know for Bowman for example more points in dex means more damage so typically they scroll their gear for about 100 str to equip better bows, but wouldn't it make just as much sense to level str to 100 and scroll for dex? That way you can equip the better weapon AND the better armor that has higher base stats than things like a bathrobe which has none. Am I overthinking this or does it all just boil down to either "it gives higher damage at low levels"/"everyone does it this way so that's just the way to do it"?
Usually, you either get enough of your secondary stat from gear (zhelm, horntail pendant, etc or it's just not worth the investment. Lots of gear has no stat requirements (overall, again zhelm, maple weapons) so the few pieces that do have requirements, are just not worth it as you'll invest more in your secondary stats then it'll return for your primary stat. Weapons are an exception, as w.att is so important for most attacker classes. But then still you'll generally get lots of str from gear still so you'd want to invest AP in str as little as possible.
MW only works on base stats, so if you were to put 100 base str instead of dex, you are loosing 10 dex when using mw20. Additionally, bowman is a bit different compared to other classes because str as a 2nd stat works a little different but if we consider thief / bucc for example - Their 2nd stat is dex, and some items can only be scrolled dex (mainly helmet but also bottom), so a NL/shadower/bucc have no choice but to scroll their helmet to their 2nd stat anyway. Thats the general rule but people take it a bit too much as a hard rule you can't break. Sometimes you just need to think. For example, having dex earrings for NL is something that make no sense, for the same price you can get like 5 more luk by using Ifia earrings, so even if you are putting base dex to covert for the earrings, you still total with more luk.
Theoretically if you had mw20 you could add 91 base str, 9 base dex, and be pretty much at the same point. However, that requires you to have mw20 which not everyone does, and speaking from experience is incredibly annoying whenever you fight a boss with dispel