Execution time and throughput are two different ways of measuring speed. Execution time is the better measure for processor speed because it is less dependent on other system components. The rest of these web pages consider only execution time.
When processor performance is quantified, it is taken to be inversely proportional to execution time.
Someone who is purchasing a computer is primarily concerned with the "bottom line" - how fast it will do whatever the customer wants to do with it. The assessment needs of customers are best met by benchmarks.
Computer architects cannot rely on just performance assessment. Assessment requires an implementation of a processor, so it is of little use in designing a new processor or making modifications to an existing processor.