Wizards is being strict here since these cards would be too powerful if splashed into opposing Guilds
The Spirit Dragon is a huge flyer with an amazing enters or attacks trigger that will virtually always put a Dragon into play in this deck
But why would you want Mirror Gallery for your Deadpool deck when you could have Mirror Box
Curse of Hospitality isnt great in multiples, but its also not terrible in the same way that a card like Experimental Frenzy might be
So, while this may be a message to bump up the efficiency of your mana, its also an opportunity to look at some of the cooler lands that dont just create mana, but can also have some other unexpected benefits
Magic: The Gathering Arena rewards regular play and engagement, so keep at it, and over time, you'll see your collection grow and your decks improve