The reason I haven't done this is that it's really hard to do in a way that is meaningful.
I already do it for experience requirements that match a specific flight (e.g., long cross-country, but even that could have potentially have multiple matches).
But for most of the remaining items, it's either silly to implement, or there are reasons why it won't work the way you might hope. For example:
- Many of the requirements for a given rating are quite trivial. E.g., "500 hours of total time", or “50 hours of solo time in airplanes”. These can be viewed directly from your basic totals (which are already clickable), so adding it in ratings progress doesn't really add much value.
- More difficult are the experience requirements that can be met via multiple different subsets of flights due to alternative criteria or allowed substitutions, so the “matching flights” won’t’ tell you anything. For example, 61.159(a)(2) (ATP rating) requires 100 hours of night flight, but 61.159(b) allows each night takeoff/landing in excess of 20 to count towards one of those hours, up to a maximum of 25 hours. That is to say, you can meet this requirement with only 75 hours of night flight but 45 night takeoffs/landings. If I link to a search that shows only flights with night and you only have 75 hours of night flight, it will be hard to reconcile why this item shows as met. Or, conversely, if you have more than 100 hours of night flight and more than 45 night takeoffs/landings, which ones are the ones that contributed and which ones were disallowed because you had hit the maximum 25 substituted hours? It’s like money: asking which flights met the criteria can be like asking which dollars from your paycheck bought a given bag of potato chips.
- Sometimes, though, the query needs to be more precise than I could actually do as a search, such that even if I showed you all of the flights that contributed to a particular rating requirement you wouldn't be able to at-a-glance see how much each flight contributed. A good example of this is things like night instruction. Suppose a given flight is 3 hours long, of which you logged 2 hours of instruction and 0.8 hours of night flight. That flight would contribute MIN(Dual, Night), or 0.8 hours of night flight towards the requirement. But if you took all the flights with dual and night, the total of dual and the total of night would read more than you can count towards this; this is actually why this isn't done in the database - I get all of your flights and examine each one in turn doing computations that can get pretty arcane and specific because the rules can get pretty arcane and specific.
So it turns out that very few of the milestones actually would have interesting associated queries that you could get useful results from and which would actually save you any meaningful clicks/taps.
By the way, this is also why in your currency, you can click on custom currencies and due dates, but most of the regulatory ones like 61.57(a/b/c) are not clickable. The custom currencies follow very regular rules, but the regulatory ones have two many different paths to completion.