i'm not sure that's actually true. as a company they've claimed some impressive numbers, but i've seen some compelling arguments that they are drastically exaggerated. they use unverifiable things like "number of wallets" as data, when many of those wallets are abandoned and inactive. i've had dozens of blockchain.info wallets over the years, used as throwaway wallets. they're probably counting all of them. they also count transactions that use their "broadcast" service as being transactions made by blockchain.info "users." i use their push service all the time, but i'm using my electrum wallet to craft and sign the transactions.

i'd avoid web wallets altogether. if you must, use greenaddress. they are recommended by bitcoin.org, they have implemented segwit and multi-sig, and they are generally more secure and reliable than blockchain.info.

as i implied, though, i prefer a lightweight desktop client like electrum myself.