I know the answer but I wonder if you do?
If you spoke to your insurance company (you do have insurance don't you?) would they say that was an acceptable methodology and do you feel confident giving out such advice as that and tying your set up to an anchor point such as a van, tree is 'sound and good' advice?
I don't know how Mike or Matt 'anchors' their set up but I am sure it would be with bolts as a minimum of standard. They are both professionals and though I don't use a rope system at all I would only work from a drilled anchor point if I had to do it this way. They may do it another way! but irrespective of how it is carried out it must be acceptable to insurers, particularly if (god forbid) you need to action the policy.
I clean all of my roofs from MEWP. I have just looked at another roof clean that has been priced to include an 85 MEWP and the plan is to boom across the ridge and drop down the other side of both buildings.
Looking at the way you give out advice and what is in that advice would tell me that you don't fit the title of 'professional'.
Now that may be personal and your level of professional is clearly different to mine and you may not see there are levels of service that are above your level, by a long way.
I would suggest you stop giving out 'bad' advice and think before you engage your frustrated viewpoint
Have a good evening 'stetson' boy
. Does this fit?
Rob