Yes indeed, carbon offsets themselves are often just accounting trickery, equating things that are unequal.
A carbon pricing scheme/national market quota/cap-and-trade works somewhat, so long as the supply of permitted pollution is made to dwindle over time. It's a good balance to give polluters time to make investment into less-polluting technology as the price of continuing the way things are is made more expensive, while rewarding firms that reduced their pollution, and being fair to consumers who aren't one of the major sources of pollution.
Carbon offsets have faced increasing criticism in recent years from academic research showing that most do not represent real emissions reductions. Studies estimate only 12% of offset projects achieve reductions. Critics argue offsets allow polluters to continue business as usual by buying cheap credits instead of reducing their own emissions. Climate & Capitalism discusses how these issues have been identified for over a decade, with early analyses finding a third to two-thirds of Clean Development Mechanism offsets did not cut emissions. The article notes parallels between worthless offsets and the subprime mortgage crisis. Experts have long argued against tree planting offsets due to issues like permanence, measurability and the delay between planting and carbon sequestration.
One early proponent admits offsets were never meant as a long-term solution, but to start a conversation on carbon that is now overdue to move forward.