If you know the format of SMR, then you can trivially see the read performance is not impacted. Writing is impacted, because it has to write multiple times for each sector write (because of overlapping sectors that allow the extra density).
Impacted write performance, coupled with hdds are generally slow with random writes PLUS the extra potential for data loss due to less-atomic sector writes, makes them terrible drives for everything except archival usage.
If you know the format of SMR, then you can trivially see the read performance is not impacted. Writing is impacted, because it has to write multiple times for each sector write (because of overlapping sectors that allow the extra density).
Impacted write performance, coupled with hdds are generally slow with random writes PLUS the extra potential for data loss due to less-atomic sector writes, makes them terrible drives for everything except archival usage.