"Why not hatch a 1/ 8192 shiny"
Okay, let me time how long it takes to hatch a party of 5 eggs. Okay, about 9 minutes.
Now, since 1/8192 is the average chance:
8192 divided by 5 is 1638.4, so now we have to multiply that by 9. That is 14746.6 minutes. That's 246.5 hours, or 10.3 days of constant hunting. Completely unreasonable to expect people to do that.
Now, let's see how long it takes to SR. Okay, about 12 seconds (some Pokemon take 10, some take 14, some take 30, 12 seems like a reasonable number for most.) That means we can do 5 in one minute. Now let's divide 8192 by 5 to find out how many minutes it will take: 1638.2 minutes, 27.3 hours, 1.13 days of constant hunting.. That´s a LOT less than 10.3 days.
Now let's see how long it takes to hatch 1366 eggs. 1366 divided by 5 is 273.2, multiplied by 9 is 2548.8 minutes, 40.98 hours, 1.7 days of constant hunting, 13.68 hours more than it takes to do 8192 SRs.
You've got to love math.