As described in problem (2) in issue 832393, some features are enabled/disabled in SetRuntimeFeaturesDefaultsAndUpdateFromArgs() using the following pattern:
WebRuntimeFeatures::Enable<FeatureName>(base::FeatureList::IsEnabled(features::k<FeatureName>)). This pattern appears to be harmful and should be avoided.

Quickly reviewing features that use it, most appear to happen to mostly work correctly due to a variety of current states and workarounds, some which I've described below. By avoiding this pattern, though, we can avoid the need to update SetRuntimeFeaturesDefaultsAndUpdateFromArgs() when runtime_enabled_features.json5 or the base::Feature's default is updated, eliminate workarounds, and avoid potential unexpected behavior.

The following is a sampling of features that use this pattern and how it affects them. They focus on "experimental" features when --enable-experimental-web-platform-features is used, but similar problems could exist for features affected by SetRuntimeFeatureDefaultsForPlatform() or elsewhere.

* UserActivationV2 is fine now since it is not "experimental" (it has no status), but this code will need to change if/when its status becomes "experimental".
* WebXR is a concrete example of such a change, as it had to be switched to use an if statement when its status was changed to "experimental" in https://crrev.com/c/1003041.
* WebAuth gets away with this pattern mostly because the base::Feature is enabled by default except on Android. However, on Android, it probably does not respect --enable-experimental-web-platform-features
* WebAssemblyStreaming is "experimental" but the base::Feature enabled by default.
* ScrollAnchoring uses the pattern but adds `|| enableExperimentalWebPlatformFeatures`, so it actually behaves correctly. However, this means this code and runtime_enabled_features.json5 need to be kept in sync and really just duplicates the work that the earlier EnableExperimentalFeatures(true) call tried to handle earlier.
* RootLayerScrolling is "stable" and thus unaffected by --enable-experimental-web-platform-features.