And not every Unreal post gets to the front page. The exact same link was submitted way earlier and if the dupe check would have worked this wouldn't be on the front page because nobody would have seen it.
4.11 - now
4.10 - https://news.ycombinator.com/item?id=10548139 [75 comments]
4.9 - https://news.ycombinator.com/item?id=10147368 [50 comments]
4.8 - https://news.ycombinator.com/item?id=9694885 [98 comments]
4.7 - https://news.ycombinator.com/item?id=9103050 [88 comments]
??? (when they released UE4 for free) - https://news.ycombinator.com/item?id=9132815 [240 comments]
4.0 - https://news.ycombinator.com/item?id=7429774 [163 comments]
But it's probably as you say. Not every interesting post (which also depends on the readers interests, of course) get's to the front page. Coupled with the bigger mindshare of Unreal, and the not so interesting Cryengine releases in the past (especially compared to Unreal) we get more Unreal postings on HN.
I've used Unity, Cryengine and Unreal. Crytek has some great tech but they are very deficient in supporting the community and Epic has invested a huge amount of resources into training, content, tools and even no-strings attached grants for devs working in Unreal. I'm not surprised at all that this has translated to more goodwill for Ue4 on HN than other engines.
Even strictly just on the PC gaming side of things, Unreal's adoption rate among game devs is miles and miles ahead of CryEngine. Is it really that hard to imagine why the community cares more about Unreal Engine than CryEngine?
This has been true for years, idTech, while being arguably technically more impressive, was being written about far less because while it's ostensibly licensable, nobody actually did it.