The high margin makes sense if their account is mostly ordering low-volume. The margins on cut-tape, for example, are nuts. As a distributor they order in bulk at low per-unit pricing, and then when hobbyists buy onsies twosies they can charge low-volume pricing for a huge markup.
Doesn't mean they're making a lot of money on those types of orders.
(That isn't an argument against the author's complaints, just providing hopefully interesting info).
I don't think the margins are that crazy. Looking at a bog standard 0603 0.1uF MLCC, they're often $0.02ea on a full reel of 4000 or $0.03ea at a cut tape of 100. So, Mouser makes a whole extra dollar to cut and bag a tape for me. For an 0402, they charge $0.02ea @100 or $0.011ea @50K. So, they make an extra $0.90 by letting me order 100 instead of 50K. 0603 10K resistor: $0.008ea @100 instead of $0.004ea @1000 (5000 is a reel).
Doesn't mean they're making a lot of money on those types of orders.
(That isn't an argument against the author's complaints, just providing hopefully interesting info).
Off-topic: I clicked through to the author's Sir Box-a-Lot project (https://lcamtuf.coredump.cx/sir-box-a-lot/) and immediately fell in love with the micro rocker switch they used for the power switch. A 7mmx3mm rocker power switch. https://www.mouser.com/datasheet/2/295/GW-1663576.pdf What an absolute beaut.