Using Docker / containers makes sense only if you need to standardize deployment pipelines. Otherwise it’s a waste of time.

When do you need to standardize anything? When you're dealing with a a large quantity.

So, either you:

1. Have many (as in, double digits) microservices comprising one system, or
2. Are in a very large organization with many development teams.

So if you have one or two apps running on Heroku / Beanstalk — leave them there. You’re not missing out on anything. It's pure overhead.