In addition to the comments below, I think a way to implement your idea is to have certain technologies automatically shared between trading partners and/or all

In addition to the comments below, I think a way to implement your idea is to have certain technologies automatically shared between trading partners and/or alliances - and also wars. This exists in other 4X games but not really any of the Civ series IIRC. You can trade generic science points but certain technologies and civics could be shared directly by trade and military engagements with foreign powers (wheel, military tactics, currency, printing press, etc).