Let’s say just like for example like MacOS. It’s awesome we have so many tools but at the same time lack of some kind of standardization can seem like nothing works and you get overwhelmed. I’m asking for people that want to support Linux or not so tech-savy people.
While I understand the sentiment, we have to understand that Open Source developers work on projects that motivate them.
So, we can have a single example of each of these but they do necessarily get any more devs. In fact, if you take economic theory ( competition for example ), it is likely they attract less attention individually than they do competing as part of an ecosystem.
It would certainly help on the user acceptance and commercial software side where choice is an impediment. But, if we are just talking resources, limiting the number of projects only works if you pay people to work on them.
Why was each of these projects started ( eg. window managers )? The answer is simple. It is because the founding developer did not like any of the existing options.