The fact the Sendgrid even has to do re-training in the first place is the problem. They only need to do and handful of things well and keeping their users accounts secure is arguably the most important. If they are having issues like this this far along in their lifespan, it's a sign of more systemic issues in their company and does not instil much confidence to potential/current customers. Wanting to switch vendors doesn't seem weird at all to me.