I follow the Delta Green/Unspeakable Oath podcast on this when they were talking about the topic. Yes you can find some information on computers for some things but if it's not some insane cultists putting up crazy stuff online, the documents you find will either be 20 generation Xerox scans of something that might be a summon spell or a lolcat picture or (holding it the wrong direction) a coupon for a free cheesesteak sandwich or just the publication information for some book. Just having the contents of some mythos tome either in a library or online is just paper & words, not until you put all the stuff together with a variety of skills is when things get messy & deadly.
Case in point, something more well known to occultists. Look at the Key of Solomon online & just how many damn versions there are, some being real, others fake, others really really fake. Same goes for the mythos as the main people unhinged enough to put it online have such a low sanity after reading it that it won't make any sense.
So for Keepers, if you are playing a modern game & your players want to look things up on their phone, just think of ways for the signal to get blocked/misinterpreted/broken then they should be sufficiently unprepared for the thing following them. Also remember what Lovecraft said about putting together the pieces of a puzzle (not a good thing & they might just want to end it now).