That wasn't really the company's fault - their mower engine supplier (Tecumseh) began having problems when it was forced to change designs to comply with EPA regs. Tecumseh eventually moved entirely out of North America in search of cheaper labor, and I believe it finally shut down a year or two later. Their older engines were actually very good, though - Toro used them as well.
Sears finally switched most of the mower line to Briggs & Stratton engines around ten years ago. Maybe a few top-end models with Honda engines.
I remember Tecumseh. My dad gave me a gas powered Sears brand walk behind edger with a Tecumseh engine. My wife called it “the beast”. When I’d fire it up on the side walk, little kids playing on my street would run home screaming and hide. lol