Honest curious question: Is it really considered that much of a faux-pas to wear a suit to a tech interview nowadays?
To answer your question, no: in Japan there are many technical interviews where it's completely reasonable to wear a suit. It really depends in which part of the planet you live, and what company you apply for.
On a personal note, I always wear a suit to inteviews. I don't have many suits, but they're bespoke and tailored to fit. When I put one on, it's like a mode switch; lookin' sharp, feelin' sharp. Sometimes it's even a talking point when an interview notices (although, to be fair, at least once one interviewer appeared to have slept in his clothes and looked a complete mess, and me lookin' sharp just emphasised it). I do live and work principally in the UK, though, where wearing a shirt with buttons is not seen as dressy.
I might think you're a little odd, but that's okay. Most of us are odd in some way.
It's been fun reading all the responses to my "don't ask the lunch question" post because so many people think I'm an uptight curmudgeon, but that's not true at all. I'm just aware of the line for "appropriate" during an interview.
Everything you say and do in an interview is being weighed, no matter what the interviewer says. It's simply human nature, and the interviewer is especially susceptible to it if they claim they aren't.
That said, every company culture is different, and lots of wild west startup companies have weird criteria for their culture. They may think someone who obeys authority is a bad idea and so suits are out, but shorts and flipflops are fine.
Someone else already said it, but I'll repeat it: Interviews go both ways. Each side is interviewing the other. It's in everyone's best interest for a 2-way match.