A hard limit of 400(+500) will stop spammers for sure. It will also give players the opportunity to enjoy all elements of the game, but not all at once - just in a limited way.
The game will be more survival, more difficult and will require you to rebuild the entire base from time to time and possibly change the location.
But because of that, there will be no diversity. 
Everyone would have to build only the most necessary things, and what is most necessary is dictated by the game - everyone will build the same. They will also build less ornamental (no terraces, no roofs, no mini bridges), every building in the game will look just as rough.
And just as there is a no ping limit server, there will need to be a no building limit server for the game to shine in a few screenshots.
I think every hard cap needs some variety to give players a choice. With the companions limit, they’ve made a whole system that calculates the usefulness of excess companions and chooses which to remove (if there are too many). The same should be the system with which players can interact and slightly reduce or increase the amount of the limit of companions or buildings.
I mean all players, not only those in the clan (because adding people to the clan is just such a system that changes the hard limit value). Solo players suffer in the current system. And repeating the companions limit system for structures is a step backwards. 
The building limit is almost certain. I’d like them to try a little bit to adjust the companion limit better (upgrade it / give it some 
love) before introducing a building cap. 
I am glad that someone continues the topic, suggests solutions and and continues talking about it, therefore gives the thread a like. 
Note: There is a game for kids that has a system for detecting if the shape of a building does not resemble certain parts of the body. So a system that detects spammers or a spider web building could be created, the question is, is it profitable to create one? 
Most likely not. Unless they accept the challenge! 