Why contracts often set the limit to 1 transaction purchase (+mint) of their ERC721 token?
For example: only 20 NFTs can be bought and minted in 1 transaction
Is there any security reasons?
Does it secure to give the address a possibility to buy and mint all, for example, 1000 NFTs in 1 transaction?
The most logical explanation off the top of my head is to give everyone a fair chance at buying the NFTs. NFTs are already a gas war, imagine you only have 10k total NFTs and you can mint a max of 1k NFTs, you only need 7 transactions to be fully minted so this is not fair for other participants.
The other reasonable explanation is gas costs, I'm not sure how much it costs to mint 1 NFT but perhaps minting 1k NFTs might break the gas limit on a block.