The Norwich services takes the (now) slower route to Manchester via CLC and as such are an increasingly poor relation, don't attract long distance passengers in the same way, and not the fast service that Liverpool deserves, nor one that will meaningfully attract passengers.
I'd enjoy watching you try and say that to a crowd of early morning Warrington line commuters who are physically unable to board what remains of their services.
You have concocted a strange fantasy here, nothing more. Prior to the other tpe switching to the chat moss, it ran down what you call the "slow" line.
The tpe on the "fast" line is supposed to take 38 minutes, but any glance at RTT will show it is usually more. That has always been the case. Trains on the "slow" line take around 10 minutes longer. They also call at Liverpool South Parkway and Warrington. Two vital cogs in the region's economy.
At that time, on that line, there was a Manchester stopper - always packed and problematic due to that - the east mids, always busy and specifically protected from short forms as a result - and a TPE which was always 6 carriages long and which needed those carriages.
There has been no mad rush to the extra TPE on the "fast" line (Yes the TPEs are also overcrowded. That's big city demand Vs derisory provision for you), only a decimation of service along a line deemed in a TfN report to be the line most deserving of electrification (rather than abandonment).
It's the only direct service connecting the country's 4th biggest metro area (and its airport) to Sheffield and the East Midlands, and really that alone ought to trump nonsense supposed anecdotes and dreamt up visions of a pretend version of somewhere preferred to be believed in than the reality.