Those episodes committed many unforgivable TV sins.
It rendered the entire series pointless.
It killed the rewatch value because even random episodes could remind you of the finale and how it undermined the series as a whole.
And there are many, many other problems people have pointed out and discussed since the fateful broadcast.
Around the time How I Met Your Mother was airing its final season, a spin-off, How I Met Your Dad, was in the works.
When the news broke, networks passed on the spin-off not long after the How I Met Your Mother series finale aired. It seemed like karma.
And the end of a "How I Met Your --" franchise.
Of course, in TV land, no idea stays dead.
A new spin-off/sequel series, How I Met Your Father, has been announced.
While the initial reaction was to scream, "No, no, please for the love of G-d, no," the few details known about the project have been surprisingly reassuring.
Instead of a broadcast comedy like its predecessor, it's going to be a streaming series. This fact alone is already a huge change in How I Met Your Father's favor.
One of the chief complaints about How I Met Your Mother is it ran for too long.
The first four seasons had their not-so-stellar episodes, but the rot set in during How I Met Your Mother Season 5. While the back half of the series had some highs, the show was never as good as it was during the early years.
Ending the series at How I Met Your Mother Season 4 or earlier might have also prevented the backlash the series finale created with the choice of having Robin and Ted end up together.
Over How I Met Your Mother's nine seasons, the series constantly showed us (1) Ted, and Robin should not be together and (2) Ted letting go of Robin.
If the series had ended earlier, it wouldn't have repeated those plot points so often and possibly retained (more) fan support for Ted and Robin.
Since How I Met Your Father will be a streamer series and streamer series don't tend to have as long runs, it's unlikely to run for nine seasons.
The episode count will be shorter as well. Ten episodes were ordered for the first season, which seems to be the standard amount for a Hulu show.
Fewer seasons and smaller episode counts mean How I Met Your Father cannot stretch out its central mystery to the absurd degree How I Met Your Mother wound up doing.
One of the frustrating features of How I Met Your Mother was how it teased big revelations only for them to be underwhelming.
How I Met Your Mother Season 5 Episode 12 was the series 100th episode, and there was a lot of hype about how it was going to reveal a lot about the Mother mystery.
What happened was Ted saw the Mother's ankle and Future!Ted mentioned a lot of details about the Mother.
It was disappointing because it did not move the central arc forward despite the series dishing out information about the mother.
How I Met Your Father will not (and hopefully no one working on the series thinks otherwise) have the luxury of playing these kinds of games with the audience.
There's no time for it when a season only spans ten episodes.
No doubt there will be episodes where little or nothing about the Father is revealed, but the series will be forced to have episodes where the reveals are more substantial and move Sophie, the protagonist, closer to the goal. Furthermore, the periods between major revelations (not counting the season breaks) will be much shorter.
This should prevent the audience from feeling much of the frustration it had with How I Met Your Mother.
Another reassuring point is Hulu, and not Netflix or any other streamer who follows the binge model for releases, will be home to How I Met Your Father.
How I Met Your Mother shined more on an episodic level than it did as an overall series. Fortunately, Hulu releases new episodes weekly.
This should encourage the How I Met Your Father writers to think more about crafting good individual episodes instead of treating the series as a very long movie.
The audience benefits because there will be more time to appreciate individual episodes and scenes than if the audience could watch one episode right after another.
It would be a bridge too far to say How I Met Your Father will avoid all the pitfalls of How I Met Your Mothers because it knows what mistakes to avoid. Plenty of franchises make the same mistakes over and over again.
What's hopeful is How I Met Your Father will be different from How I Met Your Mother in ways that should help the fledgling series do a better job of telling its story.
Over to you, TV Fanatics!
Will you give How I Met Your Father a chance?
Hit the comments below.
You can watch How I Met Your Mother online at TV Fanatic.
Becca Newton is a staff writer for TV Fanatic.