I'm not sure I'd jump to that same conclusion because of the following:

1. There's a reddit thread from a year ago that mentions this exact same verbiage, so it's not a recent update to the help document, and the functionality was working for all of us until just a few days ago.

2. TP Link is not known for stellar English in their docs, and this could just be an awkward way of stating that you need the SR20 and one other smart device to use Smart Actions on the SR20. That is, it's alerting buyers of the router that they need other devices besides just the router to use that feature.

3. There's nothing in the iOS app update notes about removing support, and the behavior itself has a lot more of a "bug" feeling than a "intentionaliy removed support" feeling.

This isn't dispositive and it's of course possible that they came along and made all Smart Actions functionality dependent on owning the SR20, but I wouldn't bet on it. Here's hoping...

Edit: Thanks Tony from TP-Link for stating officially what I had suspected. :)

I'm experiencing the same issue.  Had schedule working for a year and now poof! Nothing.  Tried emailing but luck from support. 
 

Guess I'll wait and see with everyone!

@CT-techie 

@Tony 

SAME HERE.  Tony, you responded earlier today to my query about switches not controlling groups.  Eventually I noticed that all of my Smart Actions have disappeared and I am unable to save any new ones.  I get the exact same error states here previously, "We won't be able to save the smart action at this moment. Please try again later."

This is incredibly inconvenient in our home and we need a solution.  The problem started yesterday. And again, everything had been working for a year or so just fine.  It of course applies to all switches and smart plugs I own so there was no need to be swapping anything around.

@joeyjoey 

joeyjoey wrote

Been looking into this... The Kasa app might need to request permission for Local Network Access, and doesn’t seem to do so. “Local Network Access” only appears under the “Privacy” settings on all of our iOS devices. It seems apps have to request access to the local network to be added. The Kasa app doesn’t seem to request permission so it can be added. I still have the older iOS on my own phone. None of this explains why the smart actions were all deleted to begin with seeing as my personal phone was previously the only device with Kasa installed.

I already verified this as I thought it might be the case. Mine is turned on so it allows network access, and Smart Actions still doesn't work.

Well, just as suddenly as it stopped and without any troubleshooting or intervention from me, mine just started working again.
 

The list of my Smart Actions is back in the app, and they appear to be working as expected when triggered. I noticed it this morning around 7:30 A.M. EDT. 
 

I hope that is the case for all the rest of you as well. 

chrislangevin wrote

Well, just as suddenly as it stopped and without any troubleshooting or intervention from me, mine just started working again.
 

The list of my Smart Actions is back in the app, and they appear to be working as expected when triggered. I noticed it this morning around 7:30 A.M. EDT. 
 

I hope that is the case for all the rest of you as well. 

@chrislangevin 

Hah, mine too. Support actually emailed me last night to ask about my app version and iOS version. I wrote back and haven't heard anything yet but, yeah it would appear they fixed whatever was broken 

@chrislangevin 

Yup, mine have mysteriously reappeared too this morning and all seems to be working. !!!

  
Had an extremely long chat with their service last night too that was supposed to get sent up to senior engineering.  However, I was then notified via email that they were on "National Day Holiday" from the 1st to 9th and wouldn't be addressed until after that date... so very glad someone go to it!

@joeyjoey Ugh, nothing for me.  Hasn't been working for a couple of weeks apparently.  Anyone else still broken?