> There are some things that are sealed ab­strac­tions (that is, they are not leaky)... Some ex­am­ples in­clude: Lossless com­pres­sion al­go­rithms, TCP/IP, TLS PostgreSQL

Man oh man do I disagree about every one of those being a "non-leaky" abstraction. If I had a dime for every time I've had to dig under the hood in one of those... I'd have about 20 dimes