Yes, there are good reasons for the general meaning of phrases like this, but "It is easy to see that..." is a very poor choice of phrase for this meaning. Others have already suggested better phrases.
As Buffy expresses, it's not expected for advanced papers to reference, let alone prove every conclusion used. The problem here is the passive voice, and, more importantly:
It is easy to see. What is easy to see?
I see two general phrase choices:
Longer. If you want sentence flow to present a long thought, "From Y, we observe that with/from [few steps or concepts], X.", which carries the meaning more explicitly.
Shorter. What is being said is, "Y. Y => X." (Y being the conclusion the reader is expected to know, from the audience the text is written for.)
This way, you are at least specifying the subject of your sentence.
Now, if Y is something you learn in high school, you would look silly specifying it; you would look as if you're proud that you can still do high school math. You write papers for your peers.
It's a safe bet that one or more of your peers won't agree Y is obvious, but perhaps will say nothing in review to not "look dumb", when in fact s/he is your peer, just working in a different field.
Widening the audience slightly from that seems a reasonable place to be.