The main things holding back Signal usage in my case is practically nobody in my social circle using it and the desktop client not being as nice as that of Messages or Telegram, the latter being particularly relevant for myself and contacts who primarily message with their computers rather than their phones.
Signal UX is AWFUL if you have a work PC, a home PC, a phone, and a tablet.
Getting messages to flow across all of them is impossible.
A short term compromise would just be to keep existing PWA support where it's Safari/WebKit only. That seems strictly better.
Their real argument (to shareholders etc) is that they want that 30% rake on everything you buy, so they want you to have 900 apps on your phone instead of a web browser than visits 900 websites.