New tile can also be installed over compromised substrate leading to people cutting corners like.. not putting in a tile where it should be... or simply doing a job without a replacement title when they needed one, cut corners and skip it.. because it will be assumed covered by the toilet fixture and isn't supporting the fixture. HENCE THE WHOLE PICTURE ANALOGY.
Bozos break stuff and cut corners all the time when doing replacements because they aren't setup necessarily to build the thing from scratch. You keep referring to how it would have been installed new - and won't recognize the wild west of "I'm here to fix the toilet.. I'll do whatever I need to make it look complete" or what conditions may have been created after the fact by damage.
I'm talking about standards because it's clear from that video that that fixture is full of substandard work. Grout is falling out of the joints. The caulk job is trying to cover too large of width. The caulk is trying to cover gaps. The caulk job is sloppy all over the fixture. The caulk job is separating from the fixture. This was a poor job. We don't know if it was a poor job after the fact or when built. But its clearly a crap job someone left as 'good enough'. With that level of acceptable standard of work, there is no telling what other skeletons they left behind the finish work.
Let's also remember what is the primary cause of Grout failure? MOVEMENT. What causes movement? substandard SUBSTRATE!
