When the data is consistent for several years you should already figure out that Seagate is not going to improve so fast, when they do improve in BackBlaze data you can start buying them again.
Large companies may buy Seagate due to the price advantage and the fact that their storage systems can better handle the drive failure rate.
The Seagate drives do seem to be improving in reliability though. The higher capacity Seagate drives which I presume are newer models have better failure rate numbers than the lower capacity drives. The 4 and 6TB drives seem to have reasonable failure rates compared to the other manufactures - only HGST is better than Seagate for the 4TB and Seagate 6TB drive has a lower failure rate than the HGST 8TB. FOr >4TB drives the Seagate 6TB has the lowest failure rate.
6TB 1.89%
4TB 2.19/2.99% (depending on model)
3TB 5.1/28.34% (depending on model)
2TB 10.1%
1.5TB 10.16%/23.86% (depending on model)
Large companies may buy Seagate due to the price advantage and the fact that their storage systems can better handle the drive failure rate.