So he hinted at it with, &quot;App Engine was stateless&quot;. You can&#x27;t hold a model in memory on the server with App Engine. You can if you own the server.<p>Also, App Engine has request length limits (like many platforms). This means you can&#x27;t hold a persistent connection for real time communication, and you can&#x27;t run long tasks. Even using App Engine Backends or Tasks are time-limited to about 10 minutes, and your long-running task will often be killed unexpectedly.<p>Last I checked, App Engine was using an old version of Go, and I don&#x27;t know if they&#x27;ll ever move off Python 2.7.<p>As a platform App Engine is great, but it&#x27;s not the perfect fit for everything.<p>Disclosure: I used to work for Workiva.