Seems like the Tiagra-equipped mid-level bikes get the pass but when we talk "components" mid-level starts at 105. When 5700 105 was mid-level it was praised for almost the same qualities as one would use to praise the Tiagra group today. Performance bike hasn't updated their Basic-Guide: Introduction to Shimano Road Groups but wrote the following about 105.

105: 105 is Shimano’s mid-tier group, and is currently available as a 10-speed mechanical group. Most of the features found on Dura-Ace and Ultegra can be found on the 105 groups, and it is cross compatible with 10-speed Dura-Ace and Ultegra groups. Features like “under the cable cable routing”, ergonomic levers and high-end rear derailleur performance put 105 in a league of its own when it comes to performance and value.

With the exception of "under the cable cable routing" (sic), Tiagra makes no compromises to the old 105.

Of course the groupsets have changed over the years and what was mid-level yesterday, might not make the grade today. But the process by which a bike is deemed worthy of riding depends on a great deal more than the groupset it comes equipped with. That's why you can buy an Edmonda 5 S, a Raleigh Militis 1, a Giant Defy Advanced 3, or a Ridley Fenix C40. All carbon fiber-framed Tiagra-equipped bikes that sit squarely in the mid-level road bike category.

There a tendency to "105" stuff. If it doesn't have 105 it doesn't make the grade. But 105 and Tiagra are closer in performance today than they have even been. So much so that many, not all, manufacturer's are putting it on frames you wouldn't have imagined it on in the past.

BTW, It was rude to change your post. Sorry about that. A bit of drama, I'm afraid, to lighten the reception of what has been heated discussion of late. You're a good sport to play along.