Most security features are, yeah.

The cost in terms of freedom/flexibility and reliability/longevity is very high. But we're told, this is necessary, it's the only way to guarantee the security of the poor user. But if in practice the security wasn't actually guaranteed, for most motherboards over most years, due to pretty big dumb oversights ... was it worth the extreme costs? The cost of losing compatibility with older or newer software/hardware, of losing convenient repairs and recovery? Nope.

You sold your soul for "guaranteed security" of securing the entire boot and runtime from the lowest level hardware up ... and didn't really get it anyway.

You make it sound like security is a binary thing, which is not true.