GTO will always win in aggregate, which is what makes it perfectly optimal. But it won't necessarily have the highest chance of winning against any one particular strategy.

The tools on a Swiss Army knife are just good enough to get the job done. For any of the things it can do, you have a tool at home that will get it done much more easily. Any of those given tools will be vastly superior at the one specific job they're made for. But the Swiss Army knife will always get the job done. Whether or not it cuts meat better than a steak knife or opens a wine bottle better than a real corkscrew is irrelevant. You're showing up to the table not knowing which tool you'll need -- you want the one tool that never leaves you without recourse for your opponent's strategy.