You spelled it out very clearly yourself, Mr. Sorbara.
What I can say is that we've had an alternative minimum tax in Canada since 1986. It had not been significantly reformed since then until budget 2023, which announced a number of changes, including a higher rate, a higher exemption threshold and a broader base. Budget 2024 announced a couple of other changes as well.
As you stated, the objective of the alternative minimum tax is to ensure that individuals who have a number of deductions, credits or income exemptions cannot decrease their tax liability below a certain minimum.