That's nice of you to only quote the things you want people to see from the article.
"Overall vitamin losses due to cooking are relatively modest. While there are a few inconsistencies in the above tables due likely to differing samples, globally we see that, on average, cooking does destroy vitamins, but the consequences are not catastrophic. Average vitamin losses after correction for water loss range from about 10 to 25% in most cases. Also, vitamin losses correlate with what our textbook by Kreutler et al. [1987] said, but not precisely, so obviously heat is only one of the many factors which affect vitamin content."
Do you even know what modest means?