Market Capitalization is VERY important. The main reason is that it speaks to value, which very few people involved seem to care about. The market cap is also a decent indicator of relative value within the sector. You may have noticed that Bitcoin, which last year was well in excess of 50% of the entire sector is now about 1/3rd, as rivals have technologically surpassed it. I’m not sure what you mean by growth. These don’t grow like stocks or companies do. They may grow in acceptance for transactions, but currently, only a couple have the technology to do so. Plus, the creation of crypto currencies by countries such as Russia, Venezuela or Israel, means there will be massive competition and very low barriers to entry. In other words, this sector should be extremely competitive and that usually puts a lid on the prospects.