None of those other sites are even similar to Ashley Madison. There is nothing morally wrong with dating using apps or being gay. But I expect most people to agree that cheating is definitely not morally clear.

In fact, the latter ones are so ubiquitous, I think you would be hard-pressed to find a person in a major US city in their 20s who was single for a period of time in the past 5 years and haven't used one of those apps.