The villain in this is not the IRS, it is the Congress of the United States. The IRS is just a collecting agent for the tax laws they pass.
How much anyone is affected depends on their marital status and retirement income beyond Social Security. If it is expensive, they will pay taxes on up to 85 percent of their SS benefits. Younger people will be affected even if they have less retirement income from savings because their Social Security benefits will be nominally higher in dollars but not higher in real purchasing power.