Intel is a garbage company that hasn't ever innovated... they always look at the other side, copy what they do (AMD) and then market the hell out of it while also being anti-competitive vs AMD and others.
Their Atom is a great example of what happens when Intel tries to innovate, they couldn't even develop their own architecture without falling back on copying AMD (I bet you didn't know that all modern Atoms past time they were based on P3 are a Clustered multi-threading "CMT" Design very similar to bulldozer but with macro ops instead of normal op decoding). And Atom was so bad that it literally needs a 1ghz advantage to beat Jaguar, but Intel decided to give away 7 Billion dollars worth of Atoms (Contra revenue) to prevent AMD from gaining marketshare with Jaguar. But thankfully AMD landed the contract for Xb1 & PS4 and used Jaguar for that, so the architecture became quite a bit more mainstream.
Then to make matters worse, Atom chips have a fatal flaw that makes their clocks break after ~2 years of service, causing them not to boot and basically to become doorstops. Most Atom's (and Celeron/Pentium N) are affected by this bug, even though its very hard for the average person to find where Intel has marked these bugs, since they aren't public about it (you won't easily find it around the net without searching the exact right keywords) and they are still selling all these Atom boards and laptops today w/ Celeron & Pentium N that are flawed and will break.
As far as thermal throttling:
http://www.tomshardware.com/answers/id-3599511/8700-stock-cooler-question.html
^here is one such link talking about throttling but literally....
https://www.google.com/search?q=8700+stock+cooler+throttle
And oh look... plenty of threads scattered about with people having throttling issues under actual load!
Amazing what you can find if you actually put something into google.
The 8700 has a base clock speed way under that of the 8700k and when you are actually playing games, the chip will not stay at turbo speed the entire time.
https://www.gamersnexus.net/guides/3077-explaining-coffee-lake-turbo-8700k-8600k
^Read about how the turbo actually works.
Therefore the performance of the 8700 in real world tasks isn't close to the 8700k, only in things like benchmarks where the turbo can outlast the benchmark (depending on the benchmark).