Can someone tell me what the deal is with just about every other website needing to have the browser cache cleared before it will work?

This issue is so pervasive, it seems, I'm wondering why browsers have caches, if they are causing so much trouble.

People are impatient. They leave a site within 15 seconds if it doesn't load. Adding an additional 3 steps, which after a day of heavy browsing may take several minutes to complete, isn't really a solution.

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PoserPro 2014, PS CS5.5 Ext, Nikon D300. Win 8, i7-4770 @ 3.4 GHz, AMD Radeon 8570, 12 GB RAM.