In reality the official rate is used for things like imports and in most business contracts as a reference value as well as some bank-bank transactions (e.g. settling invoices from foreign service providers.) as well as being a reference for other FX rates. That means it the base for a lot of prices consumers see inside Argentina for goods and services.
Likewise hardly any physical person can go to the bank and buy dollars at the "solidarity" rate. Last numbers I recall being reported was around 300.000 persons being habilitated to buy dollars from banks in a country of 45.000.000. To buy up to US$200 per month you need to be habilitated by BCRA, ANSES and AFIP. You also need to bring your tax declaration with you to the bank. Any credit or debit card consumption in USD (e.g. including online shopping and subscriptions etc) get deducted from the US$200 limit. One must not have received any government benefit or subsidy (REPRO, ATP etc... which most employees, shareholders and business owners received at some point during the pandemic) nor can you have refinanced your credit card nor can you have had any issues with tax department nor can you have used MEP or CCL nor can you have undeclared income according to your banks own check against your accounts vs. tax declaration .... the list is quite comprehensive. You also get black listed if you get caught (or suspected of) buying dollars on behalf of someone else or caught (or suspected) of selling the dollars on the blue and spending the extra pesos (e.g. your expenditure doesn't match your declared income)
Saying this and to your point about a subsidised dollar, yes it exists. If you use your Argentine debit / credit card in Miami to settle a US$100 restaurant bill, you will need to pay your bank back around ARS 18.200. Of that, you may be able to get up to 35% (ARS 6370) back in the form of tax refunds / credits depending on your tax situation. That means your final bill could be as low as ARS 11.830. Assuming you are a unique case (like a foreigner with USD income) and have access to dollar blue or CCL (at 220, let's say) that you can actually put towards paying your bank, then your $100 dinner in Miami just cost you between US$53 and US$82 depending on if and when you get the 35% tax perception back. You can thank the argentine government and treasury for subsidising this to the tune of tens/ hundreds of millions of dollars a day just to maintain the illusion of a peso valued at 110, and then complaining it is broke and doesn't have enough reserves. In this case and many others, the only one who actually spent US$100 is the BRCA and the only who why actually received US$100 is the restaurant in Miami... everything floating around in between is just funny-money.
Wait, so what stops people from engaging in massive arbitrage spending $$$ in the US on an argentinian credit card?