We had decades of lazy game developers not using more than one core and CPUs kept up with the demands of those game developers. Consider that games are one of the most performance sensitive an average user is going to come in contact with then how on earth are you going to find a single inherently sequential problem that is enough to saturate an entire CPU core when even games, which consist of thousands of divisible sub-problems and therefore are easily parallelizable, were fine with just a single one?

I can think of hundreds of inherently sequential algorithms we are using daily but nevertheless use an insignificant amount of CPU time.

Let's take binary tree traversal. Assuming a 100ns access penalty for every pointer this means we'd need a binary tree with a depth of 10000000 and this means it would have 2^10000000 elements to saturate a modern CPU core with a single query per second. That's quite a large dataset and I'm sure that even if you converted the entire universe into RAM you could never store that much data.