The way the Flash Translation Layer works is complicated, but long story short, there's still an advantage to sequential reads and writes on SSDs. The difference in latency and throughput isn't as dramatic as with spinning disks, but is still there. Random vs sequential writes have big implications for the long term health and performance of the SSD.
AFAIK, on SSD's there is no concept/guarantee that blocks are adjacent, so a sequential read is just a bunch of random reads.