You can disagree with it but the evidence has made it quite clear to me in just one year of being a moderator.
The community alone cannot (and should not be expected to either, by the way, as it's a huge fucking waste of time) deal with a dedicated vandal troll messing with what are by all statistical accounts extremely popular and currently airing series drawing in millions of viewers every episode.
It takes one to ruin a good thing for many, and it has happened many many times over. Locks are a safeguard against that scenario incessantly repeating itself.
Furthermore, and for a completely different reason, this is a database on which millions also rely to provide stable and correct metadata. A series' episode order and other information cannot be allowed to remain in a constant state of flux and controversy due to users warring over the state of things.
A final decision in these cases is to be expected, aligned with the policies set forth and enforced by the administration and the moderators. Locks are used for this purpose as well.
You'll have to excuse my skepticism but I truly doubt that the bluRay database you contributed to does not have similar tools. TheMovieDB certainly has these options, but they are obviously better performing.
I think that future site updates for TVDB will have improvements on this aspect as it is fairly reasonable to examine the situation and understand that they are currently not adequate. If that's not the case, do not worry, we also agree and will bring it up again.