A couple of things probably made this more likely for OpenSSL than for other libraries, though I think this phenomenon (sticking with a famous library which just isn't very good) is overall just much more common than most people appreciate

1. OpenSSL is cryptography. We did explicitly tell people not to roll their own. So the first instinct of a programmer who finds X annoying ("Let's just write my own X") is ruled out by this as likely unwise or attracts backlash from their users, "What do you mean you rolled your own TLS implementation?"

2. Even the bits which aren't cryptography are niches likely entirely unrelated to the true interest of the author using OpenSSL. The C++ programmer who needs to do an HTTPS POST but mostly is doing 3D graphics could spend a month learning about the Web PKI, AES, the X.500 directory system and the Distinguished Encoding, or they could just call OpenSSL and not care.