You might be only talking about game loading times but ignoring the impact of an SSD on the general system responsivnesss. The difference is monumental. I remember a site equated early SSD testing to moving from a Core i7 920 2.66Ghz to a 6.6-7Ghz 920. That's not fake either. If you are a power user, an SSD can easily be 4-6X faster in system responsinvess than a mechanical drive. Anand once said he refuses to use a system witout an SSD and I 100% agree.
I tested a Core 2 Duo E6600 with 70 tabs in Chrome/ForeFox + running Avast full system scan antivirus vs. my laptop with 3635QM and a mechanical drive. The Core 2 Duo SSD system crushed it in overall every day email/browsing/opening word/excel/PowerPoint/Adobe responsiveness. I've tested plenty of i5/7 combinations with a 7200 rpm drive and while they feel fast brand new, 6 months down the line after installing tons of apps, programs, media and game files, the HDD becomes such a bottleneck that even overclocking and dropping 16GB of RAM does little to help the system feel less sluggish as hell. If you are the type of user who makes coffee while the computer boots or opens 1-2 apps max and runs 5-10 browser windows at most, then maybe a mechanical drive is sufficient.
Moreso, a mechanical drive with 50-75 tabs + 10 MS docs + 5 Excel Files + 6 Adobe PDF files open simultaneously without restarting the computer for 10 days becomes completely unusuable with Not Responding browser errors, Adobe Flash crashes, etc. I've down this specific testing for months.
I would not call any modern rig modern without an SSD even if it has the 5960X in it. After using an SSD for years, I can tell how slow a system with a mechanical drive us by opening 10 tabs and 5 apps quickly and seeing a Core i7 4790K come to a crawl. Moreso, if you have a tons of apps and programs starting at launch, the SSD will load them 4-6X faster, which amounts to 30 seconds vs. 2-2.5 minutes in the real world.
In 2015 I would call any system running OS on a pure mechanical drive
completely worthless:
https://m.youtube.com/watch?v=yQjc-XW0G7Y
If I had to use a modern desktop with a mechanical drive, I would become frustrated in 5 minutes. Considering a 120-128GB SSD is $70-75, it's a no brainer to get 3-6X the performance increase in overall system feel. Until you use an SSD extensively and then go back to a mechanical HDD, you don't realize how sad the latter system is. I don't know a single PC enthusiast that could ever go back to using a mechanical drive after running a semi-decent modern SSD/M.2 for the OS.