I think many of the issues in MSFS boil down to one thing, they’re not technically adept enough to understand what third party solutions work well with MSFS and what doesn’t.
For example the UK photogrammetry, the company they bought the data from seemingly has bad building modelling and unoptimized high polygon count, which is why performance is worse.
Another notable example is Meteoblue. They have fantastic weather services, but they were the wrong company to partner with since their current weather data rely on forecasts, which have proven to be wildly inaccurate, rather than the actual weather at any given moment.