directly @ the OP:
yes there is cheats, exploits and players that use them.
that being said you have to consider there is other factors that come into play and can be responsible for major power boosters, like unlocking 1st and 2nd subs, beating key bosses in HR for relics for example, cutting down blacksmith times with gems, beating quest bosses they failed a lot on before. also certain key heroes like pent, lance and pompey that will blow up your power get snapshot in rankings. for those reasons and then some more you shouldnt focus too much on power.
about the yellow and divine serial "spawn" i would like to point out that holding onto your fragments instead of to yellow runes will not cost you precious rune inventory slots/space and once you unlock the 1st and second sub you can redeem exactly the runes you need when you need them.

just FYI: on my server they used to "accuse" a couple players of being developers, staff etc, then "accused" me and now someone else. most likely its just about fake power.

then last but not least, think about it and wouldnt you expect that if there was a developer playing and he could generate his own gear to have lv 12 runes from lv 20 on, all divine runes at 65+ (or whenever he can use them) and full sirius gear at 100+?