Sometimes this is a 'more the merrier' approach but sometimes I think it is a type of social blindness, an inability to consider the dynamic. A former friend of mine did this repeatedly, creating some excruciatingly uncomfortable meet ups.
She saw herself as a bit of a local social networker i think. Would invite me to her home and then on arrival would let me know that 'oh, x will be joining us too'. It was never a bigger group but was always just one extra person that she thought I would have something in common with. Every single time she managed to invite a surprise extra where there was some sort of situation in the background making it uncomfortable to meet and make small talk. The inviting friend had I think looked for points of contact, shared interests, mutual friends etc, but made some very awkward misjudgements through not knowing the wider picture about how people might be connected or what was going on in their lives.
On one of these occasions, a surprise extra person was presented to me as having mutual friends - which indeed we did, but it was also someone I had worked with very recently in a professional situation where I had been responsible for assessing her work,. A perfectly nice woman, but very awkward indeed to meet socially by surprise on arrival, and then trapped in a room for an hour's chit chat over coffee, just the three of us. Another time, I had expected a 1:1, arrived to find someone else had been invited with whom I had mutual friends but had not previously met - but I knew through friends that she had also recently had a traumatic bereavement. She too had visibly expected a 1:1 catchup and was clearly shaken to find that her expected personal catch up at a difficult time for her had become a surprise group of three with me as a stranger to her, and she really wasn't up to light chat. Excruciating.
Eventually I raised this very uncomfortable dynamic with the friend and tried to explain how her well meant surprise networking was repeatedly creating uncomfortable situations. I don't think she really understood at all. She was someone who threw herself enthusiastically into trying to connect people socially, , but what she totally lacked was any social antennae.
I enjoy meeting new people normally, and can happily chat to most people. However, I hate being bounced into forced social encounters through someone else's inability to read the room or to consider the dynamic.
The friendship didn't survive her lack of social awareness and I no longer see her.