Can database confirm the sequential read is really sequential in SSD

In SSD, overwriting a data file means SSD has to first erase it and then write data. This can change the data layout in the SSD for the data file. MySQL has some policies to optimize random IO, e.g., read-ahead (pre-fetching). The read-ahead policy will pre-read the remaining x pages in an "extent" if prior y pages are read sequentially. From the perspective of MySQL, using consecutive offsets for pread can make reads sequential. But I doubt is it true for an SSD. In other words, pread can only confirm the **logically sequential** but not **physically sequential**? This points to another important question: does an extent (usually contains 64 pages) in MySQL must represent consecutive space for SSD. So if I am right, why do databases still make a substantial effort in converting random IO to sequential IO?