I have advocated to several people to switch from their tube amp rigs to a Kemper. Usually this is because they are amazed at the live sound I am able to achieve compared to their own live sound (several of them have played with me and could hear the Kemper vs their tube amp rigs first hand).
That stated, Kemper is not for everyone. If you use little efx, are very cost sensitive, play primarily in your basement or just jam once in a while, etc, etc, then a decent tube amp rig might be the very best solution for you.
Where I will absolutely defend my KPA rack and foot controller is in a frequent live gig use case, especially for a cover band where a wide breadth of tones need to be accomplished. Here the KPA reigns supreme IMO.
I have also seen that it is very hard for people who are used to a specific rig's workflow to change. They know the amp, and their custom foot control board setup and have no desire to change.
For me, lugging around a tube amp and a 4x12 cab along with a pedal board (and a guitar cab mic) was just way too much work and too inflexible for tone. You will never get a good Marshall sound out of a MESA triple rect or a Fender twin, but you can get all three easily from a Kemper ..... and it weighs only 11 lbs!
There is nothing wrong with using real amps. Good lord knows I gigged tube amps myself for 30 years (1983 to 2013), and I didn't switch to Kemper in order to get good tone (actually I thought I would lose tone for sure). I switched due to load in/ load out/ and setup times along with reproducibility from gig to gig. The tone was a pleasant surprise.
I would also state, that Kemper is by far the easiest, and most intuitive of the digital guitar amps to use. Still not as simple as a tube amp and pedal board perhaps, but a damn site more simple that 3 tube amps and a switcher :).