Ah yes LSM, the MEC (Main Engine Control) - the carburetor of jet engines. Along with their Pratt counterpart, the JFC (Jet Fuel Control)(MEC is/was a GE/CFM term).
Just like the carb on a high performance car, the MEC/JFC required periodic adjustment (aka "trim") to work properly.
With a hydromechanical control, as an engine deteriorated, it would accel slower (all else being equal). And the normal wear on a hydro tended to make it shift 'lean', which also slowed the accel. Just like the carb on a Jaguar, a simple turn on a few adjustment screws could fix the problem. The requirement has always been 8 seconds - if it didn't/couldn't meet that, maintenance was needed. I recall a 767 operator telling me they "trimmed" the JFC on their JT9Ds once a month
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FADEC has pretty much eliminated that as an issue. FADECs control use "N2 dot" (rate of change of N2) as the control parameter during an accel, and will simply add fuel (subject to other limits) to obtain the necessary N2 dot. Only a severely deteriorated FADEC engine (as in no EGT margin) will fail to meet the 8 second go-around accel requirements.
Not sure about the 'other guys', but Boeing hasn't delivered a non-FADEC commercial jetliner in over 10 years.