I can't think of a single instance where this has happened, at least definitely not in a not-downtown neighbourhood. Actually, I don't even think it has happened downtown.
If you tell a part of town they are zoned for 6 story buildings and then you approve an 18 story building, people are going to be upset, join community associations, and subsequently fight any changes.
The CAs currently use those kinds of "what-if" scenarios (which never happen) to scare people into becoming rigid about change, vs. remaining flexible.
Bingo. Operative word: regional. Some of the CA leadership act like they're heading up besieged fiefdoms. Bzzzt!, wrong! You're part of a whole city, get with the program.
As long as they fit into an overall regional plan...
Again, ain't gonna happen, hasn't happened, didn't happen -- not in Fairfield. Not in Fernwood. Not in Rockland. Can't speak for James Bay, although I know it hasn't happened recently.
...I buy a 2-story house in Fairfield and the surrounding buildings are zoned max 3 stories. Then the city comes along and approves a 10 story building next door. I think we can all agree that I would have a pretty strong cause for complaint.
Name me a neighbourhood where this has happened.
It's no good arguing hypotheticals (and hyperbolic ones, at that). Let's talk reality.
The closest thing recently was the Mount St. Angela brouhaha, and that was for a six-storey building knocked down to four storeys, in an area (IIRC) zoned for three storeys. Hardly scandalous.
IIRC, there are a bunch of community plans up for revision, but the atmosphere has in addition become so acrimonious that it will be difficult for what aastra calls "common sense" to prevail.
The leadership in the CAs have dug in their heels (and I say "the leadership" because I know from my own community and from talking to people in other communites that these people DO NOT represent their neighbours in the way they think they do: plenty of others disagree with them, but they don't bother to become active to say so).
And everywhere you turn, there are people ready to muddy the waters with unsubstantiated examples ("buy a 2-story house in Fairfield ...and [see] a 10 story building next door," for example) that serve to frighten uninformed residents who are only too easily coaxed from one crisis to the next.