This isn't true. Joplin is open in many ways - source, community and contribution - and has many more contributors than "official" Joplin developers. Anyone can submit a PR if they can justify a feature and develop it.
As Laurent has said, there is no need to PM people (myself included), if we want to respond then we will. Many of us are purely volunteers, I don't get paid to be involved with Joplin. The purpose of the features category is to gather support and interest from the community. If a feature is particularly desired then it will attract the attention of developers (official and community) to implement.
Your topic isn't actually novel either, if you have a look it has been mentioned before (How Am I supposed to find Notebooks when adding notes?) if you want to see prior discussion on the topic - this topic is particularly relevant as back then it also didn't attract a huge amount of attention from the community.