You'll see theres no major announcement that in April 2017 Coinbase changed it's policy and stopped paying for up to 25 transaction fees on the blockchain. Now I have no problem with this practice in itself - it was a great feature - but my problem lies in that I didn't find out until my API payments started failing.
Here's where they actually announced it: https://blog.coinbase.com/coinbase-spring-cleaning-4f27710ff...
In the middle of a blog post that's far out of sight. For a policy change of that effect I cannot believe how they conducted it.
Then there's the multitude of API problems over the years. I would send payments and the response indicated success, but I would login and see the payments were never sent from my account.
The volume of payments I send through Coinbase is far too high for two months to go by and still not know why their API just fails from time to time. They collect enough fees from instant buys and transactions that I would expect reliability and due diligence. Especially when the security of my business depends on it.