I can't really comment on how I was handling mine vs what the OP does to their laptops.. but mine held up fine for ~4.5 years in near-daily use (work machine, incl. some personal and travel use) with just a little crack at the side. After 4.5 years I had to replace the screen though. And I'm on the third battery now, so overall "replacement parts" cost was like 80 (screen) + 1x 70 (big battery) + 1x 40 (small battery).
It did not feel like a problem caused by dust. Perhaps it was due to the small tolerances in the keyboard mechanism.
The B key would only work with a very firm press.
Because the laptop was fairly new, I assumed the problem was caused by a manufacturing defect with the frame. The problem was typically worse when the laptop was cold vs. hot.
If the problem is caused by dust (which I find hard to believe due to my issue after only 4 months of ownership) the problem must only need a small obstruction in the right place to cause a key to fail.
When the key failure happens, duster does not seem to help at all.
After the replacement, I have had no other failures. It's sad that a wonderful machine can be brought down with this terrible issue.
On a side note, I am very happy with the computer overall. The four thunderbolt 3 ports allow me to run my entire setup over one connection. I run an external RX 580 in an Akitio Node Pro to 2 4k monitors. MacOS UI design in my opinion feels clean compared to Windows currently and application support is fantastic compared to ten years ago!
Just thought I would offer my insight :)
As a word of caution, I went down the MBP route myself and was recently caught with the dust under the keyboard membrane problem. You probably aren't accurately evaluating how annoying it is to randomly lose your laptop for a few weeks while they repair the keyboard. I certainly was not.