What makes you think anyone limits their computer to run only one core? I'm flabbergasted.
Many people choose the CPU that has the highest single core performance, for both gaming or real-time multimedia processing.
Games are usually optimized for a single core, or a low number of cores, not to use all 4 or 6 or 8 cores of a system. Therefore, for gaming single core performance is still very important.
You can read some opinions about people still choosing Intel because of single core performance in this very discussion.
Additionally, modern CPUs move running threads among cores to avoid a single core from overheating. It's a strategy for thermal management.
Many people choose the CPU that has the highest single core performance, for both gaming or real-time multimedia processing.
Games are usually optimized for a single core, or a low number of cores, not to use all 4 or 6 or 8 cores of a system. Therefore, for gaming single core performance is still very important.
You can read some opinions about people still choosing Intel because of single core performance in this very discussion.
Additionally, modern CPUs move running threads among cores to avoid a single core from overheating. It's a strategy for thermal management.