Exactly. I had to deal with this due to Chrome 45 blocking flash[0]. While that might not seem like something worth targeting specific browsers, Chrome's implem

Exactly. I had to deal with this due to Chrome 45 blocking flash[0]. While that might not seem like something worth targeting specific browsers, Chrome's implementation of blocking flash was an advertiser's worst nightmare. In order to render the page properly, the page would load with flash enabled on all content. It would then pause the flash runtime on all content not deemed "important". This had the wonderful effect of giving a video ad enough time to start playing a few frames and to fire the impression that results in the advertiser getting billed for showing the ad. This would be flat out fraud on our part (a major video ad exchange), so we had to aggressively avoid allowing flash ads to buy spots from chrome 45 and later. We used ua-parser and everything went very smoothly. [0] https://www.infoq.com/news/2015/08/chrome-45-flash https://www.infoq.com/news/2015/08/chrome-45-flash