There was no need to say it as the figures are correct and the claim was that Liverpool is popular as Manchester for visitors. It isn't. Manchester scores higher than Liverpool on both the meaures cited. Your last comment is pure unevidenced assumption which could apply equally to Liverpool (or not, as there's no evidence for it).
Manchester is a more central city and as such it has a greater role as a rail hub in a way that Liverpool doesn't, purely due to location. Hence it gets more trains. It's not about the value or worth of either city.
The slight issue with Manchester is the hub so gets more trains is that whilst that's reasonable, that's not a reason to restrict Liverpool from having more train services.
Taking it to a slightly extreme example, a new line is built which would allow 16tph from Manchester or Liverpool, based on the above that's a good enough reason to give Manchester all 16 services and leave Liverpool as it is.
Taking that example of 16 paths becoming available, I get the impression that many on here wouldn't even be asking for it to be split 9:7 in favour of Manchester, yet alone 8:8. Rather they would like something better than 13:3 in favour of Manchester (which is comparable to the current services towards Scotland).
Much is said about there's services if you change, well if the timings were such that the Scotland bound services from Liverpool were quite separate from the time of those from Manchester, then those willing to change trains who are travelling from Manchester could also use those services.
Whilst direct trains will normally win out over changing, there will some who would change if it means a better arrival/departure time (even if the travel time is longer, just as long as the arrival time is earlier than waiting for the next direct service) and so even if that's 5 people an hour, that's 5 people an hour more that you can fit on the direct services from Manchester.