It seems like you could easily hit those scaling issues by manually browsing the website. While I agree that it sucks to take down a site by scraping, in that specific case it sounds like the performance issues are their fault and not yours. That said, once I realized the effect my scraping had, I would (hopefully) cease my scraping.
So the thing is, I could totally believe they never saw this traffic pattern under normal load. I'd expect bar trivia scores in a certain mid-sized US city are one of those niche things where you have a very low number of uniques but each unique then pokes around on 9 or 10 pages while they're there. The fact that the site didn't crash during normal browsing was what originally led me to speculate they were maintaining an open DB connection per session. If that was indeed the issue, I could totally imagine they'd only rarely (never?) had 100+ "concurrent..ish" unique visitors.
Ok, then why couldn't you revise your scraper so that it did everything in a single session, to avoid this problem?
To me, for private, personal use, a scraper should emulate a normal human browser as much as possible to avoid causing site problems and to avoid detection. If what you're doing can be done in the background, or by a cron process at some odd hour, it doesn't have to be fast at all, and you can set the timings to be similar to a normal human.
