If you are talking pve only then you don't need a single epic item. 8 hours to level to 60, 10 minutes to buy blue lvl 60 gear from the ah with the 2k ad you get from praying 3x, and your starter artifact will put you over 10k. You can run all but 3 dungeons which have a campaign unlock (lol, vt, mc) at 10k including tiamat and win easily. So yeah if you want you can beat this game in a single weekend and not spend a dime. this is assuming you have friends who will run you through the dungeons since gl getting a group in game with less than half the gs of an older player.
If you can find ppl to run dungeons with you, you can run dailies for a week or two and unlock some gs boons and unlock the other 3 dungeons, depending on class landing at 13-15k gs which is more than enough for pitiful amount of pve content this game has, even enough to solo some of the easier 5mans.
The game doesn't have raids or any really hard content. There is only gear progression for either pvp or ability to solo more group pve content. Not that it really matters they obsoleted all of their games content with mod 5 in their neverending effort to nerf the player players ability to earn game currency without using a cc. now you can buy a full set of the best non-artigact gear with the ad you get from a few days of dailies. The only way left to gain power is from artifacts.
The thing is, until mod 5 legendaries was the valid gear progression and you were able and expected to have them. Everyone who played before mod 5 has full legendaries. They were a realistic goal for all players to achieve. They only cost 500-1mil ad which before mod 5 was 1-2 lucky drops hence a reason to run dungeons.