I think that you might confuse IPsec with SSH in this statement.
IPsec chose since the beginning "Encrypt-then-MAC", which is proven to be secure with any good encryption and MAC algorithms.
In the beginning, SSL used "MAC-then-Encrypt". This is proven to be secure only with certain combinations of MAC and encryption algorithms. Nonetheless this was not a problem for SSL, because the combinations that they used were by chance among those correct.
SSH used in the beginning "Encrypt-and-MAC", which is the worst choice, and in certain SSH variants it was actually vulnerable.
So I think that you remember some story about SSH, because IPsec got it right since the beginning.
In general IPsec has never had any problem in its purely cryptographic design choices, but its initial variants had ridiculously complex management methods, which could result in security problems due to key or access rights mishandling.
Later, IPsec was simplified, but it had already acquired a bad reputation as being extremely hard to use correctly, which allowed other VPN solutions to become much more popular, like OpenVPN, which were much easier to configure and use.