There is NEVER any kind of advantage in rushing any age in this game, beyond getting out of Bronze Age as quickly as possible.
(...or else the race to unlock the special resources as soon as you hit the Arctic/Oceanic eras of course, since GE *will* demand them!)
What ends up happening when people race through like they're in a Civvies game is;
a) Their city is pile of under-developed crap.
Few, if any GB's, especially the must-haves like Zeus/CoA/CdM, Arc, SMB/LoA, CF, Cape, etc... means they can't fight effectively, produce too few resources, have limited fp production, etc...
They won't be able to pull their weight in guild, (ie: no goods to pay their part of GE's = everyone loses out!), can't trade effectively, will crap on your ability to compete in the weekly GE rankings, and generally be a giant loadstone around your neck, dragging your entire guild down with them.
b) Events become insanely more difficult than they should be.
(ie: enjoy those constant "spend 40-50+ fps" quests when you only earn 24-30 per day!lol)
c) They'll be tadpoles forever getting eaten alive by their entire neighbourhood, watching all their goods and stuff getting routinely plundered.
Honestly, just try to explain to them that they're doing too much harm to themselves and the guild, and that this is a game that rewards taking lots of time to build up your city & power up your GB's, etc...
If they won't listen, then cut them lose - you can't help save everyone from themselves, and some people will never get it through their thick skulls that this game is anything BUT a 'race to the finish line'.
There's no point in carrying around dead weight that will only hurt the entire guild.