This term used to hold more weight back in 2017 and the years before. It still brings up heated debate. 

The debate usually centers around the Bitcoin blockchain. There are two sides: big blockers who are in favor of each block on the Bitcoin blockchain holding more information and therefore being bigger. This option versus small blockers who are proponents of small blocks.

Originally, Bitcoin's block size was limited by database locks required to process the block -- this number was at most 10000. In terms of serialized bytes this came to about 500 to 750kbytes. 

In 2010, an explicit block size limit of 1 MB was put into place by Satoshi Nakamoto who put it as a no-op due to the previously stated limit.

In 2013 March the 1 MB limit became the effective limiting factor of the block size due to a few reasons best saved for digging in the history of Bitcoin. 

The limit was believed to require a very invasive hard fork to change and therefore was put on hold for several years. But as transaction volume increased with increasing Bitcoin adoption, the limit became a factor that caused mining fees to escalate beyond reasonable levels. 

2015 saw difficult debates take place about increased the size of the blocks in order to decrease transaction fees. This in turn fueled speculation as to whether to prevent Bitcoin from temporarily or permanently splitting into separate altcoins that wanted to try different block sizes.

Bigger block sizes meant more transactions per second and reduced fees for users. 

Small blockers came on the scene and argued that a low block size limit encourages higher transaction fees that in turn incentivize miners which thus creates a more secure network. 

Small blockers also argued that increasing max block size once would set a precedent for future increases. Plus it wouldn’t be enough because all the world's future transactions on the main blockchain would need blocks that were astronomically large and unfeasible. 

In the end, a technology called Segregated Witness was developed. That, coupled with the Lightning Network, would promise to solve these debates without having to increase block sizes on the Bitcoin blockchain.