(I am not any kind of medical expert, so the value of this comment is very limited. But you did ask for general opinions.)

I think you are clearly correct about the likelihood of encountering a partner with an STD being higher than naive calculations would suggest. It isn't clear to me how much higher. If you are at least taking typical safe-sex precautions then the probability of transmission can be quite low even if your partner does have an STD; I fear there's no good substitute for actually doing the calculations, for someone who actually wants to make a sensible decision on this and would if possible like to have a lot of sex with a lot of people.

My impression (based on almost exactly zero information) is that antibiotic treatment for most STDs is very close to 100% successful at present, but I would be concerned about hastening the development of antibiotic resistance in STDs, on account of the implications for other people. (If you[1] can guarantee that if diagnosed with an STD and treated with antibiotics you will have absolutely no sex with anyone until you're definitely cured, maybe that's not a factor.)

Also, of course, antibiotics will do you no good at all if you get, say, genital herpes or HIV.

[1] Meaning a hypothetical person wondering about this stuff for practical reasons, not necessarily you.