With MAGE there is a lot of graph algorithms I can implement and run within Memgraph. Why and when would that not be sufficient? If I would need to create my own function which programing languages are supported?
Writing procedures for use by (any) database engine is recommended in 2 cases:
Writing code in your favorite language is faster - it's a fact. This is usually not the most optimal development solution, but the most economically viable.
Write your procedure when the developers of MAGE have not come up with an idea to solve your specific problem.
All languages that can be compiled to ELF are supported.