The question on the certificate of divorce comes from Deut. 24:1-4 and what is described there is the ending, the dissolution of the marriage, not the “mere dismissal” of the wife. The so divorced woman was freed to become another man's wife. Given that the penalty for adultery was death the law allowing a certificate of divorce would hardly facilitate it.
Jesus’ words at Matt. 19 clearly state the one exception that allowed divorce, not on every account, but on the one he cited, fornication. What the article calls “complete dismissal” isn't clear.
Paul's words at I Cor. 7 dealt not with dismissal or divorce but with whether, in his recommendation of singleness, it was proper for a married person to leave their partner.
According to Jesus’ words "porneia, fornication" constituted grounds for ending the marriage by the offended party.
What about the saints (many) who remained celibate or left their spouses to join a convent or monastery. Most of this happened after the other spouse’s death — but not always. Of course, the person entering the religious life had the consent of their spouse (and in some cases — children)