As noted in the post above yours, this is actually a pretty old thread. Delves have been rebalanced pretty significantly since this thread was created, including Waxface (who even got targeted nerfs alongside the general rebalancing).
600 is also much closer to the intended ilvl for T8. A lot of players who were ‘complaining’ were attempting T8 around 580 or even lower, when T8 is generally much more of a challenge regardless.