Broadly speaking the roads have remained open throughout
Apart from both Severn Bridges being closed, lorries blown onto their sides blocking motorways, buses running into falling trees.... Oh, and 3 people killed by trees striking their vehicles.
Continued running may see a handful of lines closed for, perhaps, a longer duration, but would the total number of disrupted journeys be the same? I don't claim to have a whole careers experience (I'm only a decade in), but I'd wager that there would be less cancellations.
If trains had continued to run, even if at a reduced level and at lower speed, there would have been far greater disruption: Sooner or later, trains would have struck trees or debris, and electric trains would have become stranded with the overhead wires (OLE) down. Then staff would have to be sent to attend to those incidents and, in still horrendous conditions, either make the trains fit to move, or more likely evacuate passengers onto the ballast and somehow get them, safely, to somewhere onward transport can, somehow, be arranged.
Then, removing an electric train which has struck say a tree and got its pantograph entangled with the OLE is a complex operation, requiring staff to go on top of the train to secure the pantograph down and make the OLE fit to run trains under. Something has to be sourced to haul the stricken train away, most likely a diesel loco which will require a Driver with route knowledge, firstly to go to the depot where an emergency coupling can be fitted, and then to get to the train, which may well be on a passenger-only route with therefore very few loco Drivers passed for the line, so needing another Driver to route-conduct them. And, an issue which affected such operations towards the end of my career was the operator of the assisting loco requiring their Driver to have 'traction handling experience', ie knowing how to haul a dead EMU !
Eventually this will all have been arranged, taking up a lot of resources, and Control time, and the stranded train will be removed. However, other incidents occurred during the severe weather but lines could not be examined because they were blocked by stranded trains, and the resources, locos, Drivers, OLE/PW staff etc required to carry out line exams, debris clearance and repairs had to be utilised to rescue those trains.
I remain in no doubt that Scotrail's decision did drastically reduce the overall level of disruption, the one thing I think could have been done differently was to advertise last train departure times, on key routes at least, eg 'Our services will shut down by 1600 today, the last train from Edinburgh Waverley to Glasgow Queen St will be the 1445, from Glasgow Central to Ayr the 1504', etc.