According to current (release 2.0.0) configuration Postfix delivers mails to account's mailboxes via LDA command:

/target/postfix/main.cf:64-65

# Enable Dovecot Sieve
virtual_transport = dovecot

/target/postfix/master.cf:66-71

#
# Dovecot LDA configuration
#

dovecot unix    -       n       n       -       -      pipe
  flags=DRhu user=docker argv=/usr/lib/dovecot/deliver -f ${sender} -d ${user}@${nexthop} -m ${extension}

So Postfix uses /usr/lib/dovecot/deliver util to deliver message to Dovecot. This applies some additional requirements, i.e. Postfix and Dovecot should have access to this directory under the same user and etc.

My question is:
Why not use LMTP over unix socket as this page recommends?
LMTP really simplifies configuration and decreases processes coupling.
Do I miss any caveats?