It _completely_ changes the meaning, if someone asked a question about airplanes on September 10th, 2001 or one day later. Just saying "two decades ago" with no way to reveal the original timestamp removes that context.
It's just one of a whole lot of ways the modern web goes out of its way to get in my way.
<meta property="og:question:published_time" content="2009-02-26T17:04:37Z">
Unfortunately mobile doesn't always work nicely with hover semantics.
"It's about half past two."
"It's a little before quarter to three."
However, you're completely right when it comes to timestamps exceeding a certain age. That's why in my own projects I use a mixed approach: display recently changed things in relative time and all others in absolute terms.
I also advocate to display more detailed information when the user mouses over a timestamp, just so the data is there if needed - as it is in this case.
It would even take less space:
4 hours ago
04:12AM