Choosing between CPU vs GPU upgrading

[illestrated]

Had a related thread on this but I also asked people on Facebook regarding my choice between i5-6600k + GTX 970 vs i7-6700k + GTX 960 for my first build. I got the answer I needed here (i5 + 970 for gaming performance), but I'm very curious why so many people told me to just take the i7 because it's "harder to upgrade your CPU than your GPU."

The only things I can think of that make some sense are:
- GPUs are easier to install and more "plug and play"
- Upgrading CPU could mean needing a new mobo/other components
- Assuming harder to resell a used CPU than a GPU (?)

Is there any real reason why it's harder to replace/upgrade a CPU?

 

[turkey3_scratch]

No reason to replace an I5-6600K. Waste of money, that should play AAA games for a good 5 years.