Before:

After:

Well in fact, the blacklisted_effects file does work correctly. The effects that disappear with your patch are not supposed to be hidden.
In Kdenlive up to 18.08.x, the blacklisted_effects file also contains names of effects that have an xml gui description in data/effects/*.xml
The blacklist simply avoids listing them twice.
I agree that there are too many effects listed and we should do some sorting, improve categories, remove duplicates, but this needs a carefule review of each effect...

Thanks for the feedback @mardelle. Can you clarify what you mean by listing them twice? When I run Kdenlive without the blacklisted_effects.txt file I do not notice a difference in the UI.

What is the distinction between these two effect mappings?

1. https://phabricator.kde.org/source/kdenlive/browse/master/src/effectslist/initeffects.cpp;v18.08.2$325?blame=off
2. https://phabricator.kde.org/source/kdenlive/browse/master/src/effectslist/initeffects.cpp;v18.08.2$379?blame=off

I think the confusing part is that some effects in that file appear in the UI, while others don't, and it isn't intuitively clear how that works. Let me know if there is anything I can do to support a review of these effects.