I dont think you’re thinking about this right. Stuff like DLC has never been funded from profits of a specific game, that’s not how company finances work. They may decide to create an expansion or extension of a product they weren’t planning if a product does better than expected, but a lot of time, it’s too late by then and you’ve missed the wave to capitalize on the success. Most things like this are planned pretty early on based on the projected success. The base game and the DLC might even have separate budgets.
And all that to say, the DLC shouldn’t factor into your evaluation of a game at all. If you would like the amount of content in the game if the DLC never existed, then they added enough. You aren’t owed more content because of when they developed it, that’s absurd thinking. And if it for some reason got coded into law, it wouldn’t make anyone add more content to the base game, they’d just wait until after the game is released to start developing it. Which would make for a worse experience for both the company and consumer.
I agree with the person you replied to: if a game feels incomplete, then that’s the problem. I’m not going to pay for an incomplete game, regardless if it has DLC or not. But if a game is complete and I enjoy it, I’ll pay for DLC to get more experience from it and it doesn’t matter to me when the DLC is developed.