I think you are right but Ricciardo is very close. Remember he beat Vettel in his first season at Red Bull season. However he struggled against Kyvatt in there full season together.
The curious case of Sebastian Vettel and how to rate him is really worth discussing..
For my money, it's clear based on what we've seen through his entire career that while he can be very, very good when everything is right, he is clearly not tier 1 material, 4 championships notwithstanding. Tier 1s are sublime talents that can drive anything and pretty much get the most out of it. They are not only extraordinarily fast, but supremely adaptable. Seb clearly lacks the latter quality, and is no better than average when the car's rear end isn't planted.
I think at best, he can be considered tier 2, but we haven't seen him at anything like his best for a few seasons now. Turning up and driving the wheels off of whatever machinery you've got is a quality that tier 1s all have. Seb doesn't have it, unfortunately.
Ricciardo is a damn good driver and fully capable of winning a championship given the right time & place.. but he doesn't deliver the level of performance that Hamilton/Verstappen and Alonso do. That is the thing with tier 2s and below - they will always be the 3rd or 4th most wanted drivers on the grid, and in a sport where usually only 2 or 3 drivers have a realistic shot at winning the championship most years, that means the #1 seats at the big teams are filled by the tier 1s, and everyone below that has to pray that their package somehow springs a surprise.
As the sport is today, you need to be the #1 driver at either Mercedes, Red Bull or Ferrari to win a championship.