That's because people don't actually read the data in stuff like Backblaze, they just see Seagate and go OMGWTFBBQBURNTHEMATTHESTAKE. Seagate's definitely had certain (meaning specific models) bad drives. Some people also don't understand that hard drives that don't die (figuratively) don't exist in the consumer world any more. Hard drives dying is a fact of life, especially if you have a lot of them. I've got 16 spindles right now, all Seagates and they've all been Seagates for many many years. I've had 3 drive failures in the past 5+ years.
Backblaze's dataset for Seagate is normally drastically higher than WDC/Toshiba. I'll give you HGST consistently is more reliable but they're also more expensive. For example if you look at their Q1 2017 data for 4TB drives, the Segate ST4000DM000 accounts for 2.9 million drive days, 3 times that of the next closest drive and has a 3.27% annual failure rate. It's half the price of the HGST HMS5C4040BLE640. The Toshiba and WDC drives combine for less than 15,000 drive days. With that kind of sample size disparity, I wouldn't expect the numbers to be even. The only drive that's really out of line is the ST4000DX000. I would absolutely say avoid that specific drive. But ALL the drives are under 4% annual failure rate.
Is it worth twice the price to you to drop it from 3.2% to 1.4%? For me personally, no it's not. I've got backups and RAID. The failed drives have 40,000+ hours on them. That's perfectly acceptable to me.