I dont think they are ignoring input. Of course, when soda and lots of sugar is still part of your diet all bets are off - those are the basics that have to be fixed first. This has been repeated and emphasized over and over. However, in addition you can‘t just ignore the benefits of exercise and the extra budget of a few hundred calories it provides daily.

I recommend to get an Apple Watch (or any good fitness tracker) and a smart scale. After some time you can pretty easily and reliably predict your daily weight development simply based on your most recent diet and exercise.