Welp. Your wrong. I am an American Engineer in the Automotive industry. We DO NOT design products to fail. And you buddy with the Optima probably has some sort of wiring issue, power issue, or bought it used. Optima has warranties and uphold them,
here they are. We deal with Optima's all the time. And supply our customers with them and Odyssey Batteries. They hold up for years in all sorts of applications, applications that are much more demanding than anybodies audio system, accept this person we did (and I'm sure a few more very high powered systems).
We also produce HO alternators that last for years. Most of the time they are out of warranty when problems arise, Our warranties aren't huge because people abuse these, 3 year, 30000 miles. The abused ones that their output is way higher than intended for the Alt go out within that time frame, the properly used ones don't come back after 5-6 years, 100000ish miles, and we just fix whats wrong, charge parts and labor.
I completely disagree with your notations. If you read the user manual, and use the product as intended, it will last much longer that they say it will. People generally don't use products correctly. If its flawed, warranties will take care of it.