ArcMap will always try to interpolate between cached scales, even when a dynamic source is not available. This includes continuing to zoom in to the last available cache (resampled, i.e. pixels will just get larger, and less detailed). If the data source is available, I believe it will actually use the data source. This is in the interactive window.
Printing in ArcMap, I believe, will stick with the cached levels. We have issues sometimes tht the scale that is shown in ArcMap layout is not the one that actually ends up printing, and it is typically because it needs to shift to the next cache level.
My guess is the web mapping will always use the cache tiles, if available. This is somewhat by design, 1) for speed, and 2) so the providers can control what scales are allowed and prevent users from using beyond the resolution they are collected (and/or because of licensing issues).
I'm not sure if/why it would have changed since the last update.