Generally, I would trust the compatibility matrix in the Knowledge Base, rather than trying to interpret a collection of ten sets of Release Notes, as the compatibility matrix is regularly updated. The Release Notes are a static document related to a specific release. An important perspective to keep in mind is that the contents of Release Notes are oblivious to the conditions that exist in subsequent releases. That is to say, the NPM 10.2.2 Release Notes would talk about upgrading from NPM 10.2.1 to 10.2.2, because at the time those Release Notes are written, there was only one upgrade path.. TO 10.2.2.
The interim upgrade to NPM 10.3 may have been recommended because there were significant enhancements made in that release, most notably the new interactive charting capabilities. Looking at the Release Notes for NPM 10.3, we see that it says NPM must be at 10.0 in order to successfully upgrade to 10.3, so moving from 10.2.1 to 10.3 is a documented upgrade path. Also, it appears to me that the 10.3.1 Release Notes were the last time we discussed upgrade paths in the Release Notes.
Also, if you had additional products involved in the implementation, there may be additional interim upgrade requirements, but since this appears to be an NPM-only installation, it's much less complex.
Finally, looking at the current documentation in the NPM 10.7 Administrator Guide, in the "Upgrading Orion Network Performance Monitor" section, we find that it says you can upgrade to 10.7 direct from 10.2, which is not currently consistent with the matrix in the Knowledge Base. I'm inquiring with the product management and documentation teams as to which is actually correct; specifically whether the interim upgrade to 10.3 is still a required step.