Luck or lack of it
71% MF isn’t a lot. All magic find does is increase the chances of getting nicer things. The wiki page will explain it better than I can:
http://wiki.guildwars2.com/wiki/Magic_find
Chloe (Version 3):
[i7 930 @ 4.1Ghz (1.3875V) w/Cooler Master 120M][Gigabyte G1 Gaming GTX 970 (stock)]
Let’s say the drop tables have a 1% chance to get a green item. With 71% MF, you’d have a 1.71% chance. If the drop table chance to get a green item is really .5%, then your chance would be .855%. Different rare things have different tables, and we don’t know the various drop rates. We can infer two things through empirical evidence: (1) blues have a better drop rate than greens, greens than yellows, yellow than orange; and (2) over time, with a random distribution, someone with 71% MF all the time will get better drops than someone with none because there is a bigger range of numbers that will produce the rarer results. This may not manifest in any given finite time frame, however, because it’s random.