I agree 1000%, I believe it's up to you as the fish keeper to responsibly research the fish that you are interested in getting and not on someone else to tell you how big it's going to get what water parameters it needs what tank size it needs. There's so much information out today that this is not a hard thing to do. Yes the stores should be somewhat responsible but ultimately it's up to you to look into what you're getting before you buy it.NO; because there are many things you need to know about a species before you buy it - i'll list a few:
size
group/single
hard/soft water
temperature range
aggression level
jumper
delicate/robust
activity level
require strong current, gentle current or no current
.
.
.
Some sites do list more information - aquaticarts, impericaltropical, ... but while they may list more information they don't list enough to determine if it is suitable for your environment. You should imho understand the fish you are buying before you buy it - else you might walk into your local petco and buy the famous red-tail shark or common pleco....
Yes back in the day before cell phones it would be nice if the stores would let you know, however back then they didn't have the diversity that they do now. Also nowadays you have your cell phone on you and how hard is it to do a quick search about what you're looking at before you buy it? There's so much information that hand that is a poor excuse to blame the individuals who are selling the fish for not giving you all the information you need to make an educated purchase, understanding the long-term needs of this animal.