well, pgp bashing seems to be kind of modern these days (there seems to be a market for that, as someone else pointed out somewhere 
and it is easy to criticize something without the need to give a better alternative.
only few real alternatives to pgp exist - and i do not think any one is better. please keep in mind that pgp is not just a message encryption format, it’s a federated message encryption format. signal, whatsapp etc are often mentioned in this context - but they are centralized which introduces a lot of different problems (central data collection, network effect, easy to block and so on)
of course, there are many problems with pgp, email and all its messyness (reading tip: Xyiv -- off and online developments, on and off-topic [long]). you can be sure, the delta devs know them best - eg. we never used gpg, avoid keyservers, prefer-encryption by default, remove complexity by supporting only a subset and so on. as a result of these efforts, eg. delta chat was not affected by efail.