It doesn't have an iGPU.
It, and the 7740X are 'hated' for a few reasons:
A)It's bloody X-series. HEDT X-series. You know, for prosumers/professionals/folks that just want to blow cash?
Intel took 2 mainstream cpus, made them compatible on the X platform, and advertised them as affordable, gaming cpus with the option to upgrade to even more powerful gaming cpus.
WTH is a gaming cpu doing on the X platform?
B)The platform is flat-out more expensive.
7640X or 7740X from back then: 242 - 339USD
Aftermarket cooler: doesn't need anything too crazy, but if you go too cheap, you kill your future cpu upgrade options and have to spend more for another one... rather counter-intuitive.
The cost of a decent X299 mobo: 200+USD
Quad channel ram: What? You're really gonna put dual channel in a quad channel board? What kind of sense does that make? Price: I don't remember anymore, but it wasn't cheap either.
VS
7600K or 7700K: 242 - 339USD... Imagine that. Same price.
Aftermarket cooler: nothing too crazy - under 100USD easy
A decent Z170/270 could be had under 200USD for sure
Dual channel kit
By the way, WTH is a gaming cpu doing on the X platform? Plus, quad channel is useless for that. Even if the user does go dual channel, just why? It doesn't make sense on that platform.
C)The bios bullcrap that caused some people to kill their cpus.
If one is upgrading from either quad core cpu to the 6 core or higher models, and they do not clear/reset CMOS before hitting that power switch... Fsst. Hey, that's your new cpu dead, by the way...
The quad cores ran with different, higher voltage applications. When CMOS isn't reset, those voltage settings also get applied to the 6 core and higher - they don't like those higher settings, by the way.
Take the 6+ core models and switch in the quads? Works without a hitch.
This wouldn't have been a thing because, "Hey, why's a gaming cpu on the X platform?"
D)Overclocking?

What? A 7600K and 7700K would've done the same for less.
You see, a 7640X and 7740X are the 7600K and 7700K without iGPUs - and Intel charged the same price, even though it was removed from them? Hello? Intel F SKU - although they did come later.
Gaming cpu. X platform. Why.
E)Upgrade to 6+ cores.
They are worse at gaming because of the higher latency caused by the new(at the time) mesh bus.
Workarounds:
-Overclock cache frequency, which was limited. It quickly jacked up operating thermals, even more so than traditional core overclocking.
-Memory frequency as high as possible = expensive.
Cooling these cpus was no joke either, especially overclocking - avoid air coolers.
F)Marketing BC.
The whole thing was stupid and the mess could've been avoided.
What I see: Intel was looking to cash in on unsuspecting gamers, and they succeeded.
X299 offered nothing for those folks, except if they happened to find a professional use for their PC later.
Rant over.