The tile usage policy says, in bold letters:
OpenStreetMap data is free for everyone to use. Our tile servers are not.
Where appropriate, I have been pointing people at that policy, especially in cases where third-party map suppliers and their customers have been contacting the DWG and “demanding that we fix the problem”.
I’ve also (of course) linked to some of the summary posts in the other thread that explains why they are seeing what they are seeing. Most people don’t understand how web browsers and web servers work, just that they do - and it’s sometimes difficult to communicate that the problem tiles likely only exist in their own web browser’s cache.
I’ve also referred people to other helpful resources explaining how they can use OSM data in different ways, in a similar way to my answers in the other thread and elsewhere.