>We do not fully understand the motivations that led to the public APIs and internal complexity we’ve described here. We’ve done our best to reverse engineer them by asking “what would motivate someone to do this” and often we’ve found ourselves coming up short.
Surely they thought of it but didn't say it out loud... to keep it exploitable, maybe?
No, that's not what's being implied. They're just saying they don't understand why OpenSSL has added so many indirections to otherwise straightforward operations.
Source: I am friends with the maintainers who wrote this and was one of the people who reviewed it in draft form.
Never attribute to malice what can sufficiently be explained by the love of software developers for overengineering and complexity.
Seriously, I have no trouble explaining this. Overengineering is just how many people think software development works. It's unfortunate, it causes plenty of problems, but it's not a sign of malicious intent.