Sums of a whole column in org mode tables is among the simples formulas you can write for tables. Just call the sum function (vsum?), enter the start cell and end cell, and where you want to put the result. That's it. Except that it is text only, I don't see what's more difficult, than entering a formula in a GUI spreadsheet app.
I used org-mode tables to tabulate student grades for a course I was teaching last semester. Summing single columns was okay. But I needed to drop selected assignments (had a column with 1s and 0s). And then had to figure out the percentage marks each student had in the assignment component.
It was honestly a huge pain. I could have written the formulas for this in under 15 min on a regular spreadsheet software. With org-mode I spent hours trying to figure it out. In the end I had a hacky solution that I don't want to use again.
I should write some examples for tables and put them in a repo somewhere. You are right, sometimes the examples require a bit of trying and a lot of thinking, before one can apply them. That should not be. However, once you figure it out, it is amazing ;)
M-x org-md-export-to-markdown is my friend!