2013 things exploded, for a numver of reasons.
For example, MySQL can serve a "memcached"-like query "SELECT * FROM t WHERE id = 17" in 125µs if the data is in memory.
It scales better than memcached, though, can automatically prewarm on start, and unliked memcached runs well on machines with many cores and much memory.
The cost of memcached and MySQL on bare metal are the same.
We drop memcached, gain a LOT of replicas.
Automation is really, really necessary.