Why are chisel, alch, Alva, 4 sextant T14+ maps not sustaining?

This is not the first time I've seen this post or something like it now.

I've been running chisel, alch, alva (sometimes), 4 sextant on an A4-A6 atlas over the past few days and with that level of investment am comfortably sustaining maps with enough extra to make some cash selling the t15-16s.

It makes these posts really hard to understand. Either I've been lucky over what is now a significant sample size (100+) of maps or the investment people are claiming they're doing is false.

These "i can't sustain maps" posts appear every league and other than the 1 league where GGG nerfed map drops without saying (betrayal I think?) I've never had this issue.

/r/pathofexile Thread