Many bugs in "overly complex crypto-stacks" are more like "complexity to decrypt was reduced by X%". If it took a regular attacker 1,000,000 years to crack the

Many bugs in "overly complex crypto-stacks" are more like "complexity to decrypt was reduced by X%". If it took a regular attacker 1,000,000 years to crack the encryption, it now takes only 900,000 years. So if you are not up against some state sponsored actors, these bugs in crypto stacks should be of no concern. The impact of these bugs is, instead of "nobody can read this data" now "only 10 people on this planet can read the data". That's still better than "anybody can read the data". And sure there are other kinds of bugs like downgrade attacks but even if an attacker can downgrade you to use RC4 and decrypt data in real time, you are now in the same situation as you were when not using crypto at all. Not even that: to be in the same situation as with no crypto at all, the attacker would need to downgrade/break encryption and signing because breaking only one of both would still not allow modifying the data stream. Bugs in crypto stacks that allow code execution or memory reads/writes on the server or client are rather rare.