This is a blunt, cynical, and highly pessimistic attitude that is an absolute slurr against any DM with a half decent or complicated plot where mysteries beyond the dreams of PCs are woven subtley behind a diffuse cloud of obsfucation.
The fact that it is also 100% accurate is mere coincidence!
I can understand the sentiment, but if you look at it a bit more deeply its not really that much of an issue. The ritual costs 3600 gp to cast. The DM should be saying to himself "OK, the party can learn some things for 3600 gp OR they can learn them more cheaply some other way, but that won't be so easy...".
Plus I think there are some fairly decent limits on the Oracles already. The information has to be known by a "creature". This probably excludes things like gods, primordials, etc. You aren't going to learn the deep secrets of the Multiverse just by casting a ritual or two.
The Oracles can only answer very straightforward questions. First you need to know how to ask the right question. The answer may not be all that useful either, as other posters have pointed out. Oracles only answer in a word or brief phrase as well, so you aren't going to learn the battle plan of the Orc Army. Information COULD also be inaccurate since much of what people think they know as facts is not accurate.
All this means that the DM can certainly make the ritual useful. It could give exactly what you need but at a higher price than other options. The DM can answer other questions in ways that don't break the plot but still help the party and make casting it worthwhile.
Honestly the issue I have with this ritual is more the burden it puts on the DM to anticipate its use than anything else. Pretty much any DM who allows it into the player's hands is going to have to come up with a way to answer the questions BEFORE the players think to use the ritual, which could well mean a good bit of careful thinking.