A team where the Engineering Lead(or any kind of manager) thinks that you don't need retros because there are no problems is exactly the kind of team that needs retros.
A retro obligates people to find and/or bring up issues. In my opinion an open door policy would push people to bring up things that actually matter.
If it's the latter, then "priming the pump" is a useful exercise, and a regular retrospective makes tons of sense.
That's also generally true of processes: every team has its quirks, and you fit the processes to the team's quirks.