I have come across the following phrase from an online article : (extract from https://www3.nhk.or.jp/news/easy/k10011524021000/k10011524021000.html).
I get the meaning of the phrase, but my difficulties are about きたりしたため。
a. Is it right to think that it originates from 来る and the form「～たりする」to express multiple actions (or states) ? but to me, there is only one action stated in the phrase...now I am very confused.
b. Would it be incorrect to use ために instead of ため in this phrase ?