In which case, wouldn't the best solution be to ignore them..?
Eh... no, I wouldn't say 'ignore' the author of the article... but rather acknowledge what the author is saying, and then just check ourselves as we play.
When we play, will our characters or the game world do things that would be considered racist, sexist, homophobic, ableist, ageist, etc. etc. if they were a part of the "real world"? If so... then we just try and recognize whether we are propping up those things in the game as being "right" and "good" or point out to each other and ourselves that they are "wrong".
When Hollywood makes a movie about the Holocaust, that doesn't mean its "representation" on screen means Hollywood is supporting the Holocaust. Likewise, if someone writes a book about those people who fought against the Equal Rights Amendment (like Phyllis Schaffly) it doesn't mean that the author is also in favor of disregarding the rights of Women. You can create things that show the worst parts of our culture while also being against them.
And by the same token... if a D&D game has tieflings as a race ostracized and shunted off to their own sections of a town, it doesn't mean the players who are playing the game that have this are
in favor of doing that to people. It just means the players are trying to represent something fictionally that
has actually happened in our pasts and in many places
still happens... and it's how those players resolve those scenarios that will give us hints about how they might actually think about it. And as the guys mentioned a bit in the video... the hope would be playing a tiefling that fights against that racial repression, and becomes a hero despite it.