Tours used to lose money by the time you factored in all the costs of a single gig. The venues cut, all the tour crew who set-up and tear down, ensure all the equipment is ready, all the vehicles, drivers, fuel, food/drink, sleeping arrangements etc etc etc. The only thing that made them profitable was tour merchandise sales.
If you can cut down the amount of gear you need, you cut down the size of crew you need, number of vehicles and fuel bills etc. Valve amps are big, heavy, not 'reliable' on the road so need back ups to back ups and lots of spare valves which can be replaced by a small rack mount AxeFX with a single back up just in case. You don't need cabs and mics as venues tend to have their own PA and use in-ear monitors and don't need stage monitors. Don't need an Iso Booth to stop the Mic on the cabs picking up Background or trying to set it up the same, the mic in the exact right spot. If you don't have an iso booth, you may get a different sound due to the cab being in a different room with different acoustics. More variables, more things that can affect the sound from one gig to the next.
You can literally but your entire rig in a back pack these days - your pedal board, Amp, Cab, Mic and all the cabling linking all those replaced with a single Helix (or similar) just need a cable for your guitar and Helix to FoH and that 'sound' is ALWAYS the same. You can back up all your presets too so even if your equipment fails, you can easily load in your presets to a replacement. It can be small, light, reliable and consistent, Therefore significantly reduce the amount of gear you need to carry to a gig, reduce the amount of crew, drivers, vehicles etc and reduce the 'cost' for doing a gig making it more viable for profitability.
Not saying one is 'better' or 'worse' - they are just tools to enable a musician to use to suit their needs/situation. What maybe the right tool for one in a certain situation may not be the right one for another - but at least there are viable tools for all...