Funny thing is, my desktop CPU is now 5 years old... And still totally fine, including for games.
The CPU in the LG G2 is waaaaaaaaay slower than a 5 year old desktop chip (using Q6600 as a random 7 year old reference). It's probably on par with a 5-6 year old laptop cpu's performance (C2D or something in a Macbook air)
The CPU in the LG G2 was not designed nor expected to run in a desktop power envelope. As a result, if you tried to increase the voltage and frequency as far as you could I would expect:
1) You'd still be no where near the 100W envelope.
2) You'd still behind the Q6600 in performance
It's a little weird to compare CPUs targeting different segments. Perf/power is optimized around the typical usage of specific segment and a CPU will eat up as much of the power envelope it can for that segment. You can still compare performance/Watt but you can't directly use that to compare a smartphone experience vs a desktop experience.
(Disclaimer: I may be biased

)
Edit: An ant can carry 100x its own body weight. I would be pleased if I could carry 50% of mine. But we can't conclude that an ant is therefore stronger than me. (I hope)