Have owned front loaders for more years that one cares to remember and have not once been bothered by mould. Well the vintage Miele came with a bad problem in that regard, soon saw to setting that right.
If one uses proper detergents and keeps the door of a front loader open between uses, mould is so much less of a problem to almost rank nil. Many Americans insist on shutting up their front loaders after wash day, and leave the machine sitting for days at at time that way. Well mould needs warmth, food and moisture to grow, all of which happens in a front loader when it is shut up. There is also Americans insist on very large machines so they can do laundry once a week or fortnight. Again leaving a the machine shut up for that long unused is bound to cause problems. If one passes any laundromat that has front loaders, more often than not you will see all the doors to the machines left open after closing. Heck, shut up your dishwasher for several weeks and leave it unused and it will develop a whiff about it as well.
Don't bother with "cleansing" cycles either, but then again do tend to launder at least one load at temps >180F every few weeks, so that is that. Maybe once every six months or so will run a descaling wash with the Miele powder, but between using STPP in most wash loads, and Persil which contains a built-in limescale preventer, things are pretty good in that department.