- You've never had kids apparently. Plus, some things just stick to food prep bowls and utensils. Water just cleans things faster.
- Bend over the trash scraping all night? No thanks. My back will thank me. Besides, there's more to spill, and not all things just scrape off. Some things have to be scoured off with hot water, and detergent in the sink.
- See #2. Certain things adhere to cooking surfaces more tenaciously, such a certain rice dishes, melted cheese, or broiled dishes. And again, water flushes debris off faster.
- Why peel, and then painstakingly transfer every last bit slop? How slooooooow. People don't want to use their fingers to transfer slop not only because of rotten or moldy discarded portions or peelings of food, but because of fresh meat juices and the possible bacterial contamination (salmonella, etc.) Plus there is just the ick factor of slimy, filthy discard, and the resultant unnecessary handwashing versus using a disposal.
Garbage disposals are a big time and money saver, and keep the kitchen cleaner and less smelly. Since I always buy a quality unit, I've have zero problems. If you've had maintence issues, maybe you should try a different make or model or realize that decades-old data is very dated.