I can't figure out how to use proto files

I can't figure out if this is an issue with the server "otelcol" or my syntax is wrong. I tried hitting an otelcol server locally and remotely.
telemetrygen works (or at least establishes a grpc connection) so I think my grpcurl syntax is wrong.

### Running locally

```
IMAGE="ghcr.io/open-telemetry/opentelemetry-collector-releases/opentelemetry-collector:0.148.0"
docker run \
-p 127.0.0.1:4317:4317 \
-p 127.0.0.1:4318:4318 \
-p 127.0.0.1:55679:55679 \
$IMAGE
```

When I run `telemetrygen traces --otlp-insecure --traces 3` it connects over GRPC

### Trying to hit with grpcurl

```
PROTOS_REPO=https://github.com/open-telemetry/opentelemetry-proto.git

PROTO_FILES_FOLDER=/tmp/opentelemetry-proto/opentelemetry/proto
EXAMPLES_FOLDER=/tmp/opentelemetry-proto/examples

EX_TRACE=$EXAMPLES_FOLDER/trace.json
EX_METRICS=$EXAMPLES_FOLDER/metrics.json
EX_LOGS=$EXAMPLES_FOLDER/logs.json

TRACE_PROTO_PATH=$PROTO_FILES_FOLDER/trace/v1/trace.proto
METRICS_PROTO_PATH=$PROTO_FILES_FOLDER/metrics/v1/metrics.proto

TRACE_METHOD="opentelemetry.proto.collector.trace.v1.TraceService/Export"
METRICS_METHOD="opentelemetry.proto.collector.metrics.v1.MetricsService/Export"

HOST=localhost:4317
PAYLOAD=$EX_METRICS
PROTO_PATH=$METRICS_PROTO_PATH
METHOD="$METRICS_METHOD"

echo ######### Downloading proto files.... #########
CWD=$(pwd)
cd /tmp
git clone $PROTOS_REPO
cd opentelemetry-proto

echo ######### Sending test data.... #########
cat $PAYLOAD | \
grpcurl \
--plaintext \
-d @ \
-proto $PROTO_PATH \
-import-path "." \
-vv \
$HOST \
$METHOD

cd $CWD
```

### ERROR

`Error invoking method "opentelemetry.proto.collector.metrics.v1.MetricsService/Export": target server does not expose service "opentelemetry.proto.collector.metrics.v1.MetricsService" `