Your statement is misleading. Bitcoin protocol only check whether the address is valid or not.
The only way to know if an address is valid or not is to know a private key for it. Dont know that? Then you don't know if its valid address. When you use the word "valid" what you mean is just passing a simple checksum test which doesn't prove anything. I think you would be making a leap of faith to then conclude that just because it has the right "format" therefore a private key does indeed exist. maybe a small leap of faith but nonetheless still a leap of faith...
1. By valid, i mean it has valid Bitcoin address format (checksum, length, use Base58/Base32, etc.).
2. Node, miner and other software which perform TX/block verification don't have such information (private key).
You forget to quote this part, "Despite this, OP_RETURN has the advantage of not creating bogus UTXO entries, compared to some other ways of storing data in the blockchain."[1].
I didn't forget that part, it certainly is true but what do you think about this:
On OP_RETURN: There was been some confusion and misunderstanding in the community, regarding the OP_RETURN feature in 0.9 and data in the blockchain. This change is not an endorsement of storing data in the blockchain.
And then this:
Storing arbitrary data in the blockchain is still a bad idea; it is less costly and far more efficient to store non-currency data elsewhere.So they seem to be saying go ahead and misuse bitcoin to store data if you like we dont want you to but if you do then op_return works best. it's like they caved into the demand to store data by offering op_return but then chided people for considering to use it anyway. I bet satoshi wouldn't have been too excited about people using op_return or any mechanism to store data on chain.
What do i think about that? OP_RETURN is better than/not as bad as "trap address".
If it's that big, it's likely you imported wallet with lots of transaction. Besides block header, Electrum also download merkle proof to prove the transaction on block[2]. It's cost when you don't want to blindly trust someone else.
not alot of transactions at all. maybe only 2 or 3. if that. well i thought electrum would be like a wallet that didn't need to download a huge amount of blockchain data. it's a nice software but that kind of dampered my enthusiasm for it.
You might used Electrum long time ago which wasn't optimized well. If you have free time, i would suggest you to try Electrum again.