Don't you mean underestimating the power of infinitesimals that really won't even begin to add any number to your pp after they get weighted so low?
The weightages are rounded in the stats for your top ranks, but let me use them as an approximation Let's use 300pp plays. You have
18 1%, 54pp
10 2%, 60pp
6 3%, 54pp
5 4%, 60pp
4 5%, 60pp
3 6%, 54pp
3 7%, 63pp
2 8%, 48pp
3 9%, 81pp
2 10%, 60pp
11% 33pp
2 12% 72pp
13% 39pp
2 14% 84pp
15% 45pp
16% 48pp
2 17% 102pp
18% 54pp
19% 57pp
20% 60pp
21% 63pp
23% 69pp
24% 72pp
25% 75pp
26% 78pp
28% 84pp
29% 87pp
31% 90pp
32% 96pp
34% 102pp
36% 108pp
38% 114pp
40% 120pp
42% 126pp
44% 132pp
46% 138pp
49% 147pp
51% 153pp
54% 162pp
57% 171pp
60% 180pp
63% 189pp
66% 198pp
70% 210pp
74% 222pp
77% 231pp
81% 243pp
86% 258pp
90% 270pp
95% 285pp
100% 300pp
Adding these all up gives us an approximation of 6161pp. The difference between 6,000 and 6,161 (Again, the weighted percentages it's giving me are just rounding themselves), is a difference of ~2%. How is this NOT a good approximation.