The Conservatives and Liberal Democrats are in a close race to form the official opposition.
Probabilistic seat count: LAB 484 CON 64 LD 61 SNP 10 RFM 7 PC 3 GRN 3
34,558 interviews conducted online and on the telephone. The full survey can be access here > Survation survey
You’re are quite right of course. Two main weaknesses of these opinions polls, regardless of the methodology are:
the outcome is based on the moment the question was asked and;
the complex reality of voter behaviour is simplified by assuming that the change in support for each party from one election to the next is the same across all constituencies. Which fails to take into consideration the following:
Regional variations, new candidates and Issues and finally tactical voting.
So yeah in a nutshell these polls are utterly meaningless but in the absence of a crystal ball something is better than nothing, despite the crude nature of the something.