Have you not been reading the deconning-related threads?
There is a new building system being developed that does address the deconning issue whereby structures are marked for deconstruction instead of being removed immediately. Then, when a new structure is placed the marked structures are deconstructed to free enough build points. This makes rapid deconstruction of all essential structures difficult, but will not prevent malicious building attacks (where malicious players deliberately build useless bases, or place spawns over holes, etc.). An advantage of this system is that it will give players and administrators enough time to kick or ban the malicious player before they have caused major damage.
Overall, for now your best bet is to play on servers that have active administrators.
"You can't patch deconners" is unfortunately true. It means that it is simply not practical to implement a way to deny access to all malicious players on public servers. There will always be griefers and deconners out there.